Revision help links OCR GCSE 21st Century Combined Science physics P1-P3

Revision summary help OCR GCSE 21st Century Combined Science B physics exam papers - learning objectives P1-P3

physics F/H and combined science F/H papers for 2020 exams onwards

OCR Level 1/2 GCSE (Grade 9-1) in Combined Science B Physics (Twenty First Century Science) (J260) - OCR 21st Century GCSE Grade 9-1 Combined Science B Revision Summaries for physics Chapter P1 "Radiation and waves", Chapter P2 "Sustainable energy", Chapter P3 "Electric circuits" for FT Physics paper 03, HT Physics Paper 07, FT Combined Science Paper 04, HT Combined Science Paper 08

LINK for OCR 21st Century Combined Science physics chapters P4-P6

LINK for OCR 21st C Century 9-1 GCSE PHYSICS B chapters P1-P3

LINK for OCR 21st Century 9-1 GCSE PHYSICS B chapters P4-P7

Selected GCSE Physics Revision notes

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PLEASE READ CAREFULLY THE FOLLOWING POINTS before using my OCR GCSE 21st Century science B pages

1. ALL my unofficial GCSE (Grade 9-1) revision help summaries are based on the NEW 2016 official OCR 21st Century Science B (Grade 9-1) GCSE PHYSICS/combined science physics specifications.

2. Make sure you know whether you are doing separate science OCR 21st Century Science B GCSE grade 9-1 PHYSICS OR OCR GCSE 21st Century Science B Combined Science physics and double check your exam table from school, college or academy.

3. Also, make sure you know whether you are entered for a higher tier (HT) or a foundation tier (FT) OCR GCSE 21st Century science-physics course, so watch out for the (HT only) 'markers'.

4. I hope my revision pages help as you get to know my website, its very big and not always easy to navigate, but it is no substitute for making good lesson notes, trying your best on homework questions, studying your textbook, doing past papers of OCR GCSE 21st Century combined science/physics for exam question practice and, above all, attentive to your teacher's teaching!

5. I know from feedback that my gcse science summary revision pages have proved useful but they do not guarantee a high grade, that all depends on you and the factors mentioned in point 4. above. Please note that my GCSE science revision pages are designed to be used for online convenience, so, beware, printouts could be quite long!
6. It is really important that YOU cross-check, from my web pages, the learning objectives from the syllabus-specification with YOUR own lesson/revision notes and textbooks for YOUR OCR 21st Century Science B GCSE 9-1 combined science physics course.
7. OCR GCSE 21st Century Combined Science 1st physics paper, PAST PAPERS, specimen practice paper questions

8. 'Doc b's chemistry' is a big website so the Google [SEARCH] box at the bottom of each index or revision notes page can be VERY USEFUL - sometimes its better than the indexes for finding things!

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11. NOTE on grades: Foundation Tier FT grades 1 to 5  and  Higher Tier HT grades 4 to 9. In terms of old grades the following is an approximate comparison: grades 7-9 (A-A*), 4-6 (C-B), 1-3 (G-D), U (U) (from OFQUAL Jan 2018)

In OCR 9-1 GCSE Twenty First Century Science B physics courses, note the following!

Note: Combined Science Paper 04 assesses the contents of ALL the chapters of biology, chemistry and physics!

Syllabus-specification CONTENT INDEX of revision summary notes

What's assessed in this paper?    (for OCR 9-1 GCSE Twenty First Century Combined Science B physics paper)

Revision summary Chapter P1.1 What are the risks and benefits of using radiations?

Revision summary Chapter P1.2 What is climate change and what is the evidence for it?

Revision summary Chapter P1.3 How do waves behave?

Revision summary Chapter P2.1 How much energy do we use?

Revision summary Chapter P2.2 How can electricity be generated?

Chapter P3.1 What determines the current in an electric circuit?

Chapter P3.2 How do series and parallel circuits work?

Chapter P3.3 What determines the rate of energy transfer in a circuit?

Chapter P3.4 What are magnetic fields?

Chapter P3.5 How do electric motors work?

Revision SUMMARY Chapter P4: Explaining motion   (separate page)

Chapter P4.1 What are forces?

Chapter P4.2 How can we describe motion?

Chapter P4.3 What is the connection between forces and motion?

Chapter P4.4 How do we describe motion in terms of energy transfers?

Revision SUMMARY Chapter P5: Radioactive materials   (separate page)

Chapter P5.2 How can radioactive materials be used safely?

Revision SUMMARY Chapter P6: Matter – models and explanations   (separate page)

Chapter P6.1 How does energy transform matter?

Chapter P6.2 How does the particle model explain the effects of heating?

Chapter P6.3 How does the particle model relate to material under stress?

Revision SUMMARY Chapter P7: Ideas about Science   (separate page)

IaS1 What needs to be considered when investigating phenomenon scientifically?

IaS2 What conclusions can we make from data?

IaS3 How are scientific explanations developed?

IaS4 How do science and technology impact society?

Physics key ideas

Physics is the science of the fundamental concepts of field, force, radiation and particle structures, which are inter-linked to form unified models of the behaviour of the material universe. From such models, a wide range of ideas, from the broadest issue of the development of the universe over time to the numerous and detailed ways in which new technologies may be invented, have emerged. These have enriched both our basic understanding of, and our many adaptations to, our material environment.

You should be helped to understand how, through the ideas of physics, the complex and diverse phenomena of the natural world can be described in terms of a small number of key ideas which are of universal application and which include:

• the use of models, as in the particle model of matter or the wave models of light and of sound

• the concept of cause and effect in explaining such links as those between force and acceleration, or between changes in atomic nuclei and radioactive emissions

• the phenomena of ‘action at a distance’ and the related concept of the field as the key to analysing electrical, magnetic and gravitational effects

• that differences, for example between pressures or temperatures or electrical potentials, are the drivers of change

• that proportionality, for example between weight and mass of an object or between force and extension in a spring, is an important aspect of many models in science

• that physical laws and models are expressed in mathematical form.

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P1 "Radiation and waves")

Note: Combined Science Paper 04 assesses the contents of ALL the chapters of biology, chemistry and physics!

Introduction overview

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P1 "Radiation and waves")

There are two key science ideas in this chapter – the first considers the uses of electromagnetic radiation and the possible health risks of radiation, both in nature and from technological devices, which are becoming of increasing concern. The second part of the chapter considers a wave model for light and sound.

In P1 you consider the uses of electromagnetic radiation and the possible health risks of radiation, both in nature and from technological devices, which are becoming of increasing concern.

Then you study a wave model for light and sound.

In Topic P1.1 you study the model of radiation, an important scientific model for explaining how one object can affect another at a distance, and links this to the idea that all parts of the electromagnetic spectrum behave in this way. It then goes on to use the radiation model to explain how electromagnetic radiation behaves and to consider the risks and benefits of the technologies that use electromagnetic radiation. In some cases, misunderstanding the term ‘radiation’ generates unnecessary alarm. Through considering the evidence concerning the possible harmful effects of low intensity microwave radiation from devices such as mobile phones, learners learn to evaluate reported health studies and interpret levels of risk.

In Topic P1.2 you are introduced to the idea that all bodies emit radiation to explain the greenhouse effect. Evidence for global warming is explored; scientific explanations for climate change draw on ideas about the way that radiation is emitted and absorbed by different materials. There is an opportunity to use both physical analogies and computer modelling to demonstrate the explanatory power of models in science.

Topic P1.3 looks at the properties of waves they have in common and how a wave model can be used to explain a great many phenomena, both natural and artificial. The reflection and refraction of waves on water provide evidence that light and sound can be modelled as waves.

What you should have learned and experienced from KS3 science about light, sound, and waves ...

observed waves on water, spring, and strings

know the meaning of the terms longitudinal, transverse, superposition, and frequency, in the context of waves

know that sound waves are longitudinal and need a medium to travel through and that sound travels at different speeds in solids, in water, and in air

know that sound is produced when objects vibrate and that sound waves are detected by the vibrations they cause

know that light travels at a very high speed and can pass through a vacuum

know some of the similarities and differences between light waves and waves in matter

be able to use a ray model of light to describe and explain reflection in mirrors, refraction and dispersion by glass and the action of convex lenses

know that light incident on a surface may be absorbed, scattered, or reflected, and that light transfers energy from a source to an absorber, where it may cause a chemical or electrical effect.

Chapter P1.1 What are the risks and benefits of using radiations?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P1 "Radiation and waves")

A model of radiation can be used to describe and predict the effects of some processes in which one object affects another some distance away. One object (a source) emits radiation (of some kind). This spreads out from the source and transfers energy to other object(s) some distance away.

Light is one of a family of radiations, called the electromagnetic spectrum. All radiations in the electromagnetic spectrum travel at the same speed through space.

1. Be able to describe the main groupings of the electromagnetic spectrum – radio, microwave, infrared, visible (red to violet), ultraviolet, X-rays and gamma rays, that these range from long to short wavelengths, from low to high frequencies, and from low to high energies.

Practical work:

Estimating the speed of microwaves using a microwave oven.

Investigating how the intensity of radiation changes with distance from the source.

2. Be able to recall that our eyes can only detect a very limited range of frequencies in the electromagnetic spectrum.

3. Be able to recall that all electromagnetic radiation is transmitted through space with the same very high (but finite) speed.

4. Be able to explain, with examples, that electromagnetic radiation transfers energy from source to absorber

When radiation strikes an object, some may be transmitted (pass through it), or be reflected, or be absorbed. When radiation is absorbed it ceases to exist as radiation; usually it heats the absorber.

Some types of electromagnetic radiation do not just cause heating when absorbed; X-rays, gamma rays and high energy ultraviolet radiation have enough energy to remove an electron from an atom or molecule (ionisation) which can then take part in other chemical reactions.

Exposure to large amounts of ionising radiation can cause damage to living cells; smaller amounts can causes changes to cells which may make them grow in an uncontrolled way, causing cancer. Oxygen is acted on by radiation to produce ozone in the upper atmosphere. This ozone absorbs ultraviolet radiation, and protects living organisms, especially animals, from its harmful effects.

Radio waves are produced when there is an oscillating current in an electrical circuit. Radio waves are detected when the waves cause an oscillating current in a conductor.

Different parts of the electromagnetic spectrum are used for different purposes due to differences in the ways they are reflected, absorbed, or transmitted by different materials.

Developments in technology have made use of all parts of the electromagnetic spectrum; every development must be evaluated for the potential risks as well as the benefits. Data and scientific explanations of mechanisms, rather than opinion, should be used to justify decisions about new technologies.

5. Be able to recall that different substances may absorb, transmit, or reflect electromagnetic radiation in ways that depend on wavelength.

6. Be able to recall that in each atom its electrons are arranged at different distances from the nucleus, that such arrangements may change with absorption or emission of electromagnetic radiation, and that atoms can become ions by loss of outer electrons.

7. Be able to recall that changes in molecules, atoms and nuclei can generate and absorb radiations over a wide frequency range, including:

(a) gamma rays are emitted from the nuclei of atoms

(b) X-rays, ultraviolet and visible light are generated when electrons in atoms lose energy

(c) high energy ultraviolet, gamma rays and Xrays have enough energy to cause ionisation when absorbed by some atoms

(d) ultraviolet is absorbed by oxygen to produce ozone, which also absorbs ultraviolet, protecting life on Earth

(e) infrared is emitted and absorbed by molecules

8. Be able to describe how ultra-violet radiation, X-rays and gamma rays can have hazardous effects, notably on human bodily tissues.

9. Be able to give examples of some practical uses of electromagnetic radiation in the radio, microwave, infrared, visible, ultraviolet, X-ray and gamma ray regions of the spectrum.

10. (HT only) Be able to recall that radio waves can be produced by, or can themselves induce, oscillations in electrical circuits.

Chapter P1.2 What is climate change and what is the evidence for it?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P1 "Radiation and waves")

All objects emit electromagnetic radiation with a principal frequency that increases with temperature. The Earth is surrounded by an atmosphere which allows some of the electromagnetic radiation emitted by the Sun to pass through; this radiation warms the Earth’s surface when it is absorbed. The radiation emitted by the Earth, which has a lower principal frequency than that emitted by the Sun, is absorbed and re-emitted in all directions by some gases in the atmosphere; this keeps the Earth warmer than it would otherwise be and is called the greenhouse effect.

One of the main greenhouse gases in the Earth’s atmosphere is carbon dioxide, which is present in very small amounts; other greenhouse gases include methane, present in very small amounts, and water vapour. During the past two hundred years, the amount of carbon dioxide in the atmosphere has been steadily rising, largely the result of burning increased amounts of fossil fuels as an energy source and cutting down or burning forests to clear land.

Computer climate models provide evidence that human activities are causing global warming. As more data is collected using a range of technologies, the model can be refined further and better predictions made .

1. Be able to explain that all bodies emit radiation, and that the intensity and wavelength distribution of any emission depends on their temperatures.

Links - What is the evidence for climate change?

Practical work: Investigating climate change models – both physical models and computer models.

Using ideas about the way science explanations are developed when discussing climate change

Using ideas about correlation and cause when discussing evidence for climate change.

2. (HT only) Be able to explain how the temperature of a body is related to the balance between incoming radiation, absorbed radiation and radiation emitted; illustrate this balance, using everyday examples including examples of factors which determine the temperature of the Earth.

gcse physics revision notes

Chapter P1.3 How do waves behave?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P1 "Radiation and waves")

A wave is a regular disturbance that transfers energy in the direction that the wave travels, without transferring matter.

For some waves (such as waves along a rope), the disturbance of the medium as the wave passes is at right-angles to its direction of motion. This is called a transverse wave. For other waves (such as a series of compression pulses on a slinky spring), the disturbance of the medium as the wave passes is parallel to its direction of motion. This is called a longitudinal wave.

The speed of a wave depends on the medium it is travelling through. Its frequency is the number of waves each second that are made by the source. The wavelength of waves is the distance between the same points on two adjacent disturbances.

The ways in which light and sound waves reflect and refract when they meet at an interface between two materials can be modelled with water waves.

A wave model for light and sound can be used to describe and predict some behaviour of light and sound.

Refraction of light and sound can be explained by a change in speed of waves when they pass into a different medium; a change in the speed of a wave causes a change in wavelength since the frequency of the waves cannot change, and that this may cause a change in direction.

1. Be able to describe wave motion in terms of amplitude, wavelength, frequency and period.

Using the wave model to predict and explain the observed behaviour of light

Practical work: Carrying out experiments to measure the speed of waves on water and the speed of sound in air.

2. Be able to describe evidence that for both ripples on water surfaces and sound waves it is the wave and not the water or air itself that travels.

3. Be able to describe the difference between transverse and longitudinal waves.

4. Be able to describe how waves on a rope are an example of transverse waves whilst sound waves in air are longitudinal waves.

5. Be able to define wavelength and frequency.

6. Be able to recall and apply the relationship between speed, frequency and wavelength to waves , including waves on water, sound waves and across the electromagnetic spectrum:

wave speed (m/s) = frequency (Hz) x wavelength (m)

7. (a) Be able to describe how the speed of ripples on water surfaces and the speed of sound waves may be measured.

7. (b) Be able to describe how to use a ripple tank to measure the speed/frequency and wavelength of a wave.

8. (a) Be able to describe the effects of reflection and refraction of waves at material interfaces.

8. (b) Be able to describe how to measure the refraction of light through a prism.

8. (c) Be able to describe how to investigate the reflection of light off a plane mirror.

9. (HT only) Be able to recall that waves travel in different substances at different speeds and that these speeds may vary with wavelength.

10. (HT only) Be able to explain how refraction is related to differences in the speed of the waves in different substances.

11. Be able to recall that light is an electromagnetic wave.

12. Be able to recall that electromagnetic waves are transverse.

gcse physics revision notes

Chapter P2:  Sustainable energy

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P2 "Sustainable energy")

Chapter P2 Sustainable energy

Introduction overview

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P2 "Sustainable energy")

Energy supply is one of the major issues that society must address in the immediate future.

Citizens are faced with complex choices and a variety of messages from energy supply companies, environmental groups, the media, scientists and politicians. Some maintain that renewable resources are capable of meeting our future needs, some advocate nuclear power, and some argue that drastic lifestyle changes are required. Decisions about energy use, whether at a personal or a national level, need to be informed by a quantitative understanding of the situation, and this is an underlying theme of the chapter.

Topic P2.1 quantifies the energy used by electrical devices introduces calculations of efficiency and considers ways of reducing dissipation in a variety of contexts.

In Topic P2.2 you study national data on energy sources introduces a study of electricity generation and distribution; nuclear power generation, the burning of fossil fuels and renewable resources are compared and contrasted. Electrical safety in the home and a review of the energy choices available to individuals, organisations and society are also included.

What you should have learned and experienced from KS3 science about energy ...

compared energy uses and costs in domestic contexts, including calculations using a variety of units

considered a variety of processes that involve transferring energy, including heating, changing motion, burning fuels and changing position in a field

Chapter P2.1 How much energy do we use?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P2 "Sustainable energy")

Energy is considered as being stored in a limited number of ways: chemical, nuclear, kinetic, gravitational, elastic, thermal, electrostatic and electromagnetic and can be transferred from one to another by processes called working and heating.

Electricity is a convenient way to transfer energy from source to the consumer because it is easily transmitted over distances and can be used to do work in many ways, including heating and driving motors which make things move or to lift weights.

When energy is used to do work some energy is usually wasted in doing things other than the intended outcome, it is dissipated into the surroundings, ultimately into inaccessible thermal stores.

The power of an appliance or device is a measure of the amount of energy it transfers each second, i.e. the rate at which it transfers energy.

Sankey diagrams are used to show all the energy transfers in a system, including energy dissipated to the surroundings; the data can be used to calculate the efficiency of energy transfers.

1. Be able to describe how energy in chemical stores in batteries, or in fuels at the power station, is transferred by an electric current, doing work on domestic devices, such as motors or heaters.

Practical work

Comparing the power consumption of a variety of devices and relate it to the changes in stored energy.

Investigating the effects of insulation on the rate of cooling.

Calculating the cost of energy supplied by electricity given the power rating, the time and the cost per kWh.

2. Be able to explain, with reference to examples, the relationship between the power ratings for domestic electrical appliances, the time for which they are in use and the changes in stored energy when they are in use.

3. Be able to recall and apply the following equation in the context of energy transfers by electrical appliances :

energy transferred (J, kWh) = power (W, kW) x time (s, h)

4. Be able to describe, with examples, where there are energy transfers in a system, that there is no net change to the total energy of a closed system (qualitative only).

5. Be able to describe, with examples, system changes, where energy is dissipated, so that it is stored in less useful ways.

6. Be able to explain ways of reducing unwanted energy transfer e.g. through lubrication, thermal insulation.

7. Be able to describe the effects, on the rate of cooling of a building, of thickness and thermal conductivity of its walls (qualitative only).

8. Be able to recall and apply the equation ...

efficiency = useful energy transferred ÷ total energy transferred

... to calculate energy efficiency for any energy transfer,

and (HT only) be able to describe ways to increase efficiency.

9. Be able to interpret and construct Sankey diagrams to show understanding that energy is conserved.

Usefulness of electricity in the home, electrical energy transfer, cost & power calculations, P = IV = I2R, E = Pt

Energy resources and their uses - a general survey Revision Notes

Chapter P2.2: How can electricity be generated?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P2 "Sustainable energy")

The main energy resources that are available to humans are fossil fuels (oil, gas, coal), nuclear fuels, biofuels, wind, hydroelectric, tides and from the Sun.

In most power stations generators produce a voltage across a wire by spinning a magnet near the wire. Often an energy source is used to heat water; the steam produced drives a turbine which is coupled to an electrical generator. Other energy sources drive the generator directly.

The mains supply to our homes is an alternating voltage, at 50 Hz, 230 volts, but electricity is distributed through the National Grid at much higher voltages to reduce energy losses. Transformers are used to increase the voltage for transmission and then decrease the voltage for domestic use.

Most mains appliances are connected by a 3 core cable, containing live, neutral and earth wires.

The demand for energy is continually increasing and this raises issues about the availability and sustainability of energy sources and the environmental effects of using these sources. The introduction and development of new energy sources may provide new opportunities but also introduce technological and environmental challenges. The decisions about the energy sources that are used may be different for different people in different contexts.

1. Be able to describe the main energy resources available for use on Earth (including fossil fuels, nuclear fuel, biofuel, wind, hydroelectricity, the tides and the Sun)

Links - What determines the rate of energy transfer in a circuit? (P3.4)

What is the process inside a generator? (P3.7)

Practical work:  Investigating factors affecting the output from solar panels and wind turbines.

Using ideas about probability in the context of risk.

Extracting and interpreting information about electricity generation and energy use presented in a variety of numerical and graphical forms.

2. Be able to explain the differences between renewable and non-renewable energy resources.

3. Be able to compare the ways in which the main energy resources are used to generate electricity.

4. Be able to recall that the domestic supply in the UK is a.c., at 50Hz and about 230 volts and explain the difference between direct and alternating voltage.

5. Be able to recall that, in the national grid, transformers are used to transfer electrical power at high voltages from power stations, to the network and then used again to transfer power at lower voltages in each locality for domestic use.

6. Be able to recall the differences in function between the live, neutral and earth mains wires, and the potential differences between these wires; hence explain that a live wire may be dangerous even when a switch in a mains circuit is open, and explain the dangers of providing any connection between the live wire and any earthed object.

7. Be able to explain patterns and trends in the use of energy resources in domestic contexts, workplace contexts, and national contexts.

Be able to discuss the risks and benefits of different ways of generating electricity and why different decisions on the same issue might be appropriate.

Types of energy & stores - examples compared and explained, mechanical work done and power calculations

Chapter P3: Electric circuits

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

Chapter P3 Electric circuits

Introduction overview

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

Known only by its effects, electricity provides an ideal vehicle to illustrate the use and power of scientific models. During the course of the 20th century, electrical engineers completely changed whole societies, by designing systems for electrical generation and distribution, and a whole range of electrical devices.

In chapter P3 you will learn how scientists visualise what is going on inside circuits and predict circuit behaviour.

In Topic P3.2 you study models of charge moving through circuits driven by a voltage and against a resistance are introduced.

A more general understanding of voltage as potential difference is then developed in Topic P3.2/P3.3, which then continues
with an exploration of the difference between series and parallel circuits, leading on to investigating the behaviour of various components in d.c. series circuits.

Topic P3.4 concentrates on quantifying the energy transferred in electric circuits and how this is determined by both the potential difference and the current.

A reminder of earlier work on magnets and magnetic fields in Topic P3.4/P3.5 leads into an introduction to the electric motor.

In Topic P3.6 Applications of electromagnetism and in particular the electric motor have revolutionised people’s lives in so many ways – from very small motors used in medical contexts, to very large motors used to propel ships or pump water in pumped storage schemes.

What you should have learned and experienced from KS3 science about light, sound, and waves ...

be familiar with the basic properties of magnets, and use these to explain and predict observations

know that there is a magnetic field close to any wire carrying an electric current

be aware of the existence of electric charge, and understand how simple electrostatic phenomena can be explained in terms of the movement of electrons between and within objects

understand the idea of an electric circuit (a closed conducting loop containing a battery) that conducts an electric current and be able to predict the current in branches of a parallel circuit

understand the idea of as a measure of the ‘strength’ of a battery or power supply

know that electrical resistance is measured in ohms and can be calculated by dividing the voltage across the component by the current through it

know that the power ratings of electrical appliances are related to the rate at which the appliances transfers energy.

Chapter P3.1 What determines the current in an electric circuit?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

An electric current is the rate of flow of charge; in an electric circuit the metal conductors (the components and wires) contain many charges that are free to move. When a circuit is made, the battery causes these free charges to move, and these charges are not used up but flow in a continuous loop.

In a given circuit, the larger the potential difference across the power supply the bigger the current. Components (for example, resistors, lamps, motors) resist the flow of charge through them; the resistance of connecting wires is usually so small that it can be ignored. The larger the resistance in a given circuit, the smaller the current will be.

Representational models of electric circuits use physical analogies to help think about how an electric circuit works, and to predict what happens when a variable is changed.

1. Be able to recall that current is a rate of flow of charge, that for a charge to flow, a source of potential difference and a closed circuit are needed and that a current has the same value at any point in a single closed loop.

Identify limitations in analogies used to represent electric circuits.

Practical work - Designing and constructing electric circuits to investigate the electrical properties of range of circuit components.

2. Be able to recall and use the relationship between quantity of charge, current and time:

charge (C) = current (A) x time (s)

3. Be able to recall that current (I) depends on both resistance (R) and potential difference (V) and the units in which these quantities are measured.

4. (a) Be able to recall and apply the relationship between I, R, and V, to calculate the currents, potential differences and resistances in d.c. series circuits using the formula

potential difference (V) = current (A) x resistance (Ω)

4. (b) Be able to describe an experiment to investigate the resistance of a wire and be able to draw the circuit diagram of the circuit used.

5. Be able to recall that for some components the value of R remains constant (fixed resistors) but that in others it can change as the current changes (e.g. heating elements, lamp filaments).

6. (a) Be able to use graphs to explore whether circuit elements are linear or non-linear and relate the curves produced to their function and properties.

6. (b) Be able to describe experiments to investigate the I-V characteristics of circuit elements. To include: lamps, diodes, LDRs and thermistors. Be able to draw circuit diagrams for the circuits used.

7. Be able to represent circuits with the conventions of positive and negative terminals, and the symbols that represent common circuit elements, including filament lamps, diodes, LDRs and thermistors.

3. Ohm's Law, experimental investigations of resistance, I-V graphs, calculations V = IR, Q = It, E = QV

gcse physics revision

Chapter P3.2 How do series and parallel circuits work?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

When electric charge flows through a component (or device), work is done by the power supply and energy is transferred from it to the component and/or its surroundings. Potential difference measures the work done per unit charge.

In a series circuit the charge passes through all the components, so the current through each component is the same and the work done on each unit of charge by the battery must equal the total work done by the unit of charge on the components. The potential difference (p.d.) is largest across the component with the greatest resistance and a change in the resistance of one component will result in a change in the potential differences across all the components.

In a parallel circuit each charge passes through only one branch of the circuit, so the current through each branch is the same as if it were the only branch present and the work done by each unit of charge is the same for each branch and equal to the work done by the battery on each charge. The current is largest through the component with the smallest resistance, because the same battery p.d. causes a larger current to flow through a smaller resistance than through a bigger one.

When two or more resistors are placed in series the effective resistance of the combination (equivalent resistance) is equal to the sum of their resistances, because the battery has to move charges through all of them.

Two (or more) resistors in parallel provide more paths for charges to move along than either resistor on its own, so the effective resistance is less.

Some components are designed to change resistance in response to changes in the environment e.g. the resistance of an LDR varies with light intensity, the resistance of a thermistor varies with temperature; these properties used in sensing systems to monitor changes in the environment.

1. Be able to relate the potential difference between two points in the circuit to the work done on, or by, a given amount of charge as it moves between these points.

potential difference (V) = work done (energy transferred) (J) / charge (C)

Linking the features of a model or analogy to features in an electric circuit, identify evidence for specific aspects of a model and limitations in representations of a model.

Practical work:

Using d.c. series circuits, including potential divider circuits to investigate the behaviour of a variety of components.

Designing and constructing electric circuits to use a sensor for a particular purpose.

2. (a) Be able to describe the difference between series and parallel circuits: to include ideas about how the current through each component and the potential difference across each component is affected by a change in resistance of a component.

2. (b) Be able to describe how to practically investigate the brightness of bulbs in series and parallel circuits. Be able to draw circuit diagrams for the circuits used.

3. Be able to explain, why, if two resistors are in series the net resistance is increased, whereas with two in parallel the net resistance is decreased (qualitative explanation only)

4. Be able to solve problems for circuits which include resistors in series, using the concept of equivalent resistance.

5. Be able to explain the design and use of d.c. series circuits for measurement and testing purposes including exploring the effect of :

(a) changing current in filament lamps, diodes, thermistors and LDRs

(b) changing light intensity on an LDR

(c) changing temperature of a thermistor (NTC only) sensor for a particular purpose.

gcse physics revision

5. More on series and parallel circuits, circuit diagrams, measurements and calculations gcse physics revision

Chapter P3.3 What determines the rate of energy transfer in a circuit?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

The energy transferred when electric charge flows through a component (or device), depends on the amount of charge that passes and the potential difference across the component.

The power rating (in watts, W) of an electrical device is a measure of the rate at which an electrical power supply transfers energy to the device and/or its surroundings. The rate of energy transfer depends on both the potential difference and the current. The greater the potential difference, the faster the charges move through the circuit, and the more energy each charge transfers.

The National Grid uses transformers to step down the current for power transmission. The power output from a transformer cannot be greater than the power input, therefore if the current increases, the potential difference must decrease. Transmitting power with a lower current through the cables results in less power being dissipated during transmission.

1. Be able to describe the energy transfers that take place when a system is changed by work done when a current flows through a component.

Practical work - Comparing the power consumption of a variety of devices and relate it to the current passing through the device.

2. Be able to explain, with reference to examples, how the power transfer in any circuit device is related to the energy transferred from the power supply to the device and its surroundings over a given time using the formula

power (W) = energy (J) ÷ time (s)

3. Be able to recall and use the relationship between the potential difference across the component and the total charge to calculate the energy transferred in an electric circuit when a current flows through a component

energy transferred (work done) (J) = charge (C) x potential difference (V)

4. Be able to recall and apply the relationships between power transferred in any circuit device, the potential difference across it, the current through it, and its resistance

power (W) = potential difference (V) x current (A) power (W) = (current (A))2 x resistance (Ω)

Be able to use the idea of conservation of energy to show that when a transformer steps up the voltage, the

5. Be able to use the idea of conservation of energy to show that when a transformer steps up the voltage, the output current must decrease and vice versa

(a) select and use the equation:

potential difference across primary coil x current in primary coil =

potential difference across secondary coil x current in secondary coil

6. Be able to explain how transmitting power at higher voltages is more efficient way to transfer energy.

Ohm's Law, experimental investigations of resistance, I-V graphs, calculations V = IR, Q = It, E = QV

Usefulness of electricity in the home, electrical energy transfer, cost & power calculations, P = IV = I2R, E = Pt

The 'National Grid' power supply, environmental issues, use of transformers gcse physics revision notes

Chapter P3.4 What are magnetic fields?

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

Around any magnet there is a region, called the magnetic field, in which another magnet experiences a force. The magnetic effect is strongest at the poles. The field gets gradually weaker with distance from the magnet.

The direction and strength of a magnetic field can be represented by field lines. These show the direction of the force that would be experienced by the N pole of a small magnet, placed in the field.

The magnetic field around the Earth, with poles near the geographic north and south, provides evidence that the core of the Earth is magnetic. The N-pole of a magnetic compass will point towards the magnetic north pole.

Magnetic materials (such as iron and nickel) can be induced to become magnets by placing them in a magnetic field. When the field is removed permanent magnets retain their magnetisation whilst other materials lose their magnetisation.

When there is an electric current in a wire, there is a magnetic field around the wire; the field lines form concentric circles around the wire. Winding the wire into a coil (solenoid) makes the magnetic field stronger, as the fields of each turn add together. Winding the coil around an iron core makes a stronger magnetic field and an electromagnet that can be switched on and off.

In loudspeakers and headphones the magnetic field produced due to a current through a coil interacts with the field of a permanent magnet.

The 19th century discovery of this electromagnetic effect led quickly to the invention of a number of magnetic devices, including electromagnetic relays, which formed the basis of the telegraph system, leading to a communications revolution.

1. Be able to describe the attraction and repulsion between unlike and like poles for permanent magnets

Practical work

Using a plotting compasses to map the magnetic field near a permanent bar magnet, between facing like/opposite poles of two magnets, a single wire, a flat coil of wire and a solenoid.

Investigating the relationship between the number of turns on a solenoid and the strength of the magnetic field.

Building a loudspeaker.

Developments of electromagnets

2. Be able to describe the characteristics of the magnetic field of a magnet, showing how strength and direction change from one point to another.

3. Be able to explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic.

4. Be able to describe the difference between permanent and induced magnets.

5. Be able to describe how to show that a current can create a magnetic effect.

6. Be able to describe the pattern and directions of the magnetic field around a conducting wire.

7. Be able to recall that the strength of the field depends on the current and the distance from the conductor.

8. Be able to explain how the magnetic effect of a solenoid can be increased.

gcse physics revision

gcse physics notes

Chapter P3.5 How do electric motors work? (all of topic 3.5 is HT only)

(Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B physics paper 03, Topics for Chapter P3 "Electric circuits")

(HT only) The magnetic fields of a current-carrying wire and a nearby permanent magnet will interact and the wire and magnet exert a force on each other. This is called the ‘motor effect’.

If the current-carrying wire is placed at right angles to the magnetic field lines, the force will be at right angles to both the current direction and the lines of force of the field. The direction of the force can be inferred using Fleming’s left-hand rule.

The size of the force is proportional to the length of wire in the field, the current and the strength of the field.

The motor effect can result in a turning force on a rectangular current-carrying coil placed in a uniform magnetic field; this is the principle behind all electric motors.

The invention and development of practical electric motors have made an impact on almost every aspect of daily life.

1. (HT only) Be able to describe the interaction forces between a magnet and a current-carrying conductor to including ideas about magnetic fields.

Practical work

Investigating the motor effect for a single wire in a magnetic field and applying the principles to build a simple electric motor.

Building a simple electric motor and explaining how it works.

2. (HT only) Be able to show that Fleming’s left-hand rule represents the relative orientations of the force, the conductor and the magnetic field.

3.  (HT only) Be able to select and apply the equation that links the force (F) on a conductor to the strength of the field (B), the size of the current (I) and the length of conductor (l) to calculate the forces involved:

force (N) = magnetic field strength (T) × current (A) × length of conductor (m)

4.  (HT only) Be able to explain how the force on a conductor in a magnetic field is used to cause rotation in the rectangular coil of a simple electric motor

Detailed knowledge of the construction of motors is not required.

Be able to describe and explain examples of uses of electric motors that have made significant improvements to people’s lives.

11. Motor effect of an electric current, electric motor, loudspeaker, Fleming's left-hand rule, F = BIL gcse physics

PAST PAPERS   (For OCR GCSE (9–1) Twenty First Century Combined Science B physics exam papers)

for FT Physics paper 03, HT Physics Paper 07, FT Combined Science Paper 04, HT Combined Science Paper 08

OCR B GCSE Grade 9-1 Twenty First Century Science Suite

Specifications - syllabuses, past exam papers, specimen practice question papers

OCR B GCSE Twenty First Century Science (Grade 9-1) GCSE COMBINED SCIENCE B

I will add the past paper links as soon as they become available from the examination board website

OCR Twenty First Century Science GCSE 9-1 Combined Science B May June Summer Examination Papers 2018

OCR GCSE 21st Century Combined Science B J260/03 Physics Paper (Foundation Tier) May 2018

OCR GCSE 21st Century Combined Science B J260/07 Physics Paper (Higher Tier) May 2018

OCR GCSE 21st Century Combined Science B J260/04 Combined Science Paper (All sciences, Foundation tier) 2018

OCR GCSE 21st Century Combined Science B J260/08 Combined Science Paper (All sciences, Higher tier) June 2018

OCR Twenty First Century Science GCSE 9-1 Combined Science B May June Summer Examination Papers 2019

OCR GCSE 21st Century Combined Science B J260/3 Physics Foundation tier paper May 2019

OCR GCSE 21st Century Combined Science B J260/7 Physics Higher tier paper May 2019

OCR GCSE 21st Century Combined Science B J260/4 Combined Science Foundation tier paper June 2019

OCR GCSE 21st Century Combined Science B J260/8 Combined Science Higher tier paper June 2019

OCR Twenty First Century Science GCSE 9-1 Combined Science B May June Summer Examination Papers 2020

OCR GCSE 21st Century Combined Science B J260/3 Physics Foundation tier paper May-November 2020

OCR GCSE 21st Century Combined Science B J260/7 Physics Higher tier paper May-November 2020

OCR GCSE 21st Century Combined Science B J260/4 Combined Science Foundation tier paper June-November 2020

OCR GCSE 21st Century Combined Science B J260/8 Combined Science Higher tier paper June-November 2020

OCR Twenty First Century Science GCSE 9-1 Combined Science B May June Summer Examination Papers May 2021

OCR GCSE 21st Century Combined Science B J260/3 Physics Foundation tier paper May 2021

OCR GCSE 21st Century Combined Science B J260/7 Physics Higher tier paper May 2021

OCR GCSE 21st Century Combined Science B J260/4 Combined Science Foundation tier paper June 2021

OCR GCSE 21st Century Combined Science B J260/8 Combined Science Higher tier paper June 2021

ALL OCR GCSE (Grade 9-1) Level 1/Level 2 TWENTY FIRST CENTURY SCIENCE B specifications and syllabus revision summary links

Be aware that both Paper 1 and Paper 2 for biology, chemistry or physics assess content from ALL 6 chapters 1-6 !!!

Paper 1 is called "Breadth in biology/chemistry/physics" and Paper 2 is called "Depth in biology/chemistry/physics"

Watch out for HT Only sections AND make sure you know exactly which GCSE science course you are doing!

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OCR B GCSE Twenty First Century Science (Grade 9-1) GCSE PHYSICS B J259 Specification  https://www.ocr.org.uk/Images/234601-specification-accredited-gcse-twenty-first-century-science-suite-physics-b-j259.pdf OCR 21st C Science GCSE Physics B Data sheet - Twenty First Century Science Suite - Physics B OCR 21st C Science GCSE Physics B Sample assessment materials taster booklet OCR 21st C Science GCSE Physics B FT Unit J259/01 - Breadth in physics - Foundation tier - Sample assessment material OCR 21st C Science GCSE Physics B FT Unit J259/02 - Depth in physics - Foundation tier - Sample assessment material OCR 21st C Science GCSE Physics B FT Unit J259/03 - Breadth in physics - Higher tier - Sample assessment material OCR 21st C Science GCSE Physics B FT Unit J259/04 - Depth in physics - Higher tier - Sample assessment material OCR B GCSE Twenty First Century Science (Grade 9-1) GCSE COMBINED SCIENCE B J260 Specification  https://www.ocr.org.uk/Images/234597-specification-accredited-gcse-twenty-first-century-science-suite-combined-science-b-j260.pdf OCR 21st C Science GCSE Combined Science B Data sheet - Twenty First Century Science Suite - Combined Science B OCR 21st C Science GCSE Combined Science B Data sheet - Twenty First Century Science Suite - Combined Science B - Physics B OCR 21st C Science GCSE Combined Science B Sample assessment materials taster booklet OCR 21st C Science GCSE Combined Science B FT Unit J260/03 - Physics - Foundation tier - Paper 3 - Sample assessment material OCR 21st C Science GCSE Combined Science B FT Unit J260/04 - Combined science - Foundation tier - Paper 4 - Sample assessment material OCR 21st C Science GCSE Combined Science B HT Unit J260/07 - Physics - Higher tier - Paper 3 - Sample assessment material OCR 21st C Science GCSE Combined Science B HT Unit J260/08 - Combined science - Higher tier - Paper 4 - Sample assessment material higher tier level for OCR GCSE Twenty First Century Science Combined Science B physics paper 1, foundation tier level for OCR GCSE Twenty First Century Science Combined Science B physics paper 1, revision summaries for OCR GCSE Twenty First Century Science Combined Science B physics paper 1 exam, what do you need to learn for the OCR GCSE Twenty First Century Science Combined Science B physics paper 1 exam?, revision notes for the OCR GCSE Twenty First Century Science Combined Science B physics paper 1 exam, help in revising for the OCR GCSE Twenty First Century Science Combined Science B physics paper 1 exam, what do you need to know for the OCR GCSE Twenty First Century Science Combined Science B physics paper 1 paper?, guidance notes for OCR GCSE Twenty First Century Science Combined Science B physics paper 1, syllabus specification for OCR GCSE Twenty First Century Science Combined Science B physics paper 1, syllabus for OCR GCSE Twenty First Century Science Combined Science B physics paper 1, past papers for revising OCR GCSE Twenty First Century Science Combined Science B physics paper 1

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