Edexcel ScienceiGCSE Physics

Wd. Electromagnetic Induction

2019-2020

Name:________________Physics Teacher:______________

House CG

Year 11 (d)

Specification Checklist

6.01 use the following units: ampere (A), volt (V) and watt (W)

6.02 know that magnets repel and attract other magnets and attract magnetic substances

6.04 understand the term magnetic field line

6.07 describe how to use two permanent magnets to produce a uniform magnetic field pattern"

6.15 know that a voltage is induced in a conductor or a coil when it moves through a magnetic

field or when a magnetic field changes through it and describe the factors that affect the

size of the induced voltage

6.16 describe the generation of electricity by the rotation of a magnet within a coil of wire and of

a coil of wire within a magnetic field, and describe the factors that affect the size of the

induced voltage

Electromagnetic Induction – Science (Physics) 2

Electromagnetic Induction – Science (Physics) 3

Key Word Image Definition

Alternating Current (a.c.)

Current that repeatedly changes direction. This is what comes out of your plug socket.

Electromagnet A soft iron core wrapped in wire. When current flows through the coil it becomes magnetic.

Field Line An indication of the strength and direction of the magnetic field. The denser the lines the stronger the field.

Generator A machine that converts one form of energy into another, especially mechanical energy into electrical energy

Induction The induction of voltage by the motion of a conductor across a magnetic field

Left Hand Rule (Motor Effect)

The relationship between magnetic field direction, electrical current in a wire and the force on the wire while inside a magnetic field.

Magnetic Field An area where other magnetic objects experience a force of attraction and repulsion.

Key Words

1: Inducing Voltage

Knowledge and Understanding Recap QuizUse the knowledge you have gained since Shell to answer the following questions

1. What is the efficiency of a light bulb that gives out 120J of light energy when supplied with 300J of electrical energy?

……………… (3)

2. What is Hooke’s Law?

…………………………………………………………………………………………………………………………………………………………………………………… (2)

3. What is the definition of a transverse wave?

…………………………………………………………………………………………

………………………………………………………………………………………… (2)

4. What are the units of power?

…………………………………………………………………………………………

………………………………………………………………………………………… (1)

5. Sketch the magnetic field shape and direction around the magnet below.

(2)

6. What is the name given to a collection of billions of stars?

…………………………………………………………………………………………

………………………………………………………………………………………… (1)

Score [ /11]

Electromagnetic Induction – Science (Physics) 4

Learning Outcomes:

1. Describe how to induce voltage in a conducting wire. 2. Investigate the factors which affect the size of this induced voltage. 3. Explain why these factors result in a larger induced voltage.

Inducing Voltage in a Wire

Key Ideas

1. A voltage can be induced if we move a conductor (e.g. a wire) at 90o (right angles) to a magnetic field.

2. It occurs because the conductor cuts through the magnetic field lines. 3. We can say that the voltage is induced or generated in the wire. 4. This cause a current to flow in the wire5. The direction of this current depends on:

a. The direction of the magnetic fieldb. The direction of the force (movement) on the wire.

6.

Electromagnetic Induction – Science (Physics) 5

W1: Inducing Voltage in a Wire

In this investigation you are going to investigate what factors affect the size of the induced voltage in a wire.

In this investigation the method is written in the questions and will be underlined so it is vital that you work methodically through these.

W1: Method and questions

1. In this investigation, what is important about the direction of motion and the direction of the magnetic field in relation to each other?

……………………………………………………………………………………………………….……………………………………………………………………………………………………….

2. Set up a yoke with two magnets with opposite poles facing each other.

Connect a length of insulating wire to a sensitive ammeter or voltmeter.

Move the wire down between the poles of the magnet

Describe your observations as specifically as you can.

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

3. Move the wire up between the poles of the magnet

Describe your observations as specifically as you can.

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

4. Try to move the wire in such a way that you get the biggest induced voltage or current that

you can.

How did you make the induced voltage bigger?

……………………………………………………………………………………………………….

Electromagnetic Induction – Science (Physics) 6

Health and Safety Check!

Keep any strong magnetsaway from electronicdevices.

North

-+

5. Add an extra magnet to each end of the yoke.

Move the wire up and down through the magnetic field again.

How do your results compare to your results in parts 2 and 3?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

6. There is one more way to increase the induced voltage in the wire. Using your knowledge

from the Magnetism and Electromagnetism topic, can you think of a way that you might do

this?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

7. Discuss your ideas with your teacher.

In the space below sketch the set up you would need to increase the induced voltage using

your answer to part 6.

8. Test your above hypothesis.

What were your results?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

Electromagnetic Induction – Science (Physics) 7

Increasing the Induced Voltage in a Wire

Key Ideas

1. The size of the induced voltage (and current) in a wire can be increased in three ways. 2. These are:

a. Moving the wire more quickly (more field lines are cut in a given time/ field lines cut faster)

b. Using a stronger magnet (there are more magnetic field lines to cut)c. Wrapping the wire into a coil (so that more pieces of wire move through the

magnetic field).

Electromagnetic Induction – Science (Physics) 8

2: Induction in Coils

Knowledge and Understanding Recap QuizUse the knowledge you have gained since Shell to answer the following questions

1. How long will it take 600C of charge to pass a point in a wire if 8A of current is flowing?

……………… (3)

2. What is law of conservation of energy?

…………………………………………………………………………………………………………………………………………………………………………………… (2)

3. What is -60oC in K?

…………………………………………………………………………………………

………………………………………………………………………………………… (1)

4. What is the order of the EM spectrum from highest to lowest frequency?

(2)

5. Which type of radiation is the most ionising?

…………………………………………………………………………………………

………………………………………………………………………………………… (1)

6. Sketch the magnetic field shape and direction between the bar magnets below:

(3)

Score [ /12]

Electromagnetic Induction – Science (Physics) 9

Learning Outcomes:

1. Describe how a voltage can be induced in a coil of wire using a magnet2. Describe the changes that can be made to increase the size of this induced

voltage3. Explain why these changes increase the induced voltage

Inducing Voltage in a Coil

Key Ideas

1. You can also induce/generate a voltage by pushing/dropping a magnet into a coil of conducting wire.

2. The magnet (or coil) must be moving for a voltage to be induced.3. Just like before the coil is cutting the magnetic field lines of the magnet to generate the

voltage.

Electromagnetic Induction – Science (Physics) 10

W2: Inducing Voltage in a Coil

In this investigation you are going to investigate what factors affect the size of the induced voltage in a coil.

In this investigation the method is written in the questions and will be underlined so it is vital that you work methodically through these.

W2: Method and questions

1. Connect your coil to a sensitive ammeter or voltmeter using leads.

Move the magnet and coil respectively to complete to table

[Note: if using a digital ammeter, indicate the direction of needle as + or – (as it appears on

the digital display].

Moving Component

South pole towards magnet

North pole towards magnet

Direction of Ammeter Needle [left of right]

Magnet into coil

Magnet out of coil

Coil towards magnet

Coil away from magnet

Coil and magnet moved up

and down together

Electromagnetic Induction – Science (Physics) 11

Health and Safety Check!

Keep any strong magnetsaway from electronicdevices.

Ammeter or Voltmeter

2. What can you conclude from these results?

Hint: Consider the relative direction of magnet and coil.

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

3. Try to move the magnet in such a way that you get the biggest induced voltage or current

that you can.

How did you make the induced voltage bigger?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

4. Replace your coil for one with more turns.

Move the magnet through the coil again.

How do your results compare to part 1?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

5. There is one more way to increase the induced voltage in the coil. Using your knowledge

from the Magnetism and Electromagnetism topic, can you think of a way that you might do

this?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

6. Test your above hypothesis.

What were your results?

……………………………………………………………………………………………………….

……………………………………………………………………………………………………….

Summarise below the 3 way to increase the induced voltage in a coil:

1. …………………………………………………………………………………………………………

2. …………………………………………………………………………………………………………

Electromagnetic Induction – Science (Physics) 12

3. …………………………………………………………………………………………………………

Increasing the Induced Voltage in a Coil

Key Ideas

1. The size of the induced voltage (and current) in a coil can be increased in three ways. 2. These are:

a. Moving the magnet or coil more quickly (more field lines are cut in a given time/lines cut faster)

b. Using a stronger magnet (there are more magnetic field lines to cut)

Electromagnetic Induction – Science (Physics) 13

c. Having a coil with more turns (so that more pieces of wire move through the magnetic field).

Electromagnetic Induction – Science (Physics) 14

3. The Generator

Knowledge and Understanding QuizUse the knowledge you have gained since Shell to answer the following questions

1. A box weighing 550N rests on the floor on a base of area 0.75m2. What pressure is the box putting on the floor?

……………… (3)

2. A light ray hits a boundary between air and glass. On the image below add:a. The normal (1)b. The direction of the refracted ray (by eye) (1)

3. What are the names of the 3 wires in a plug?

…………………………………………………………………………………………

………………………………………………………………………………………… (3)

4. A car accelerates from 5m/s to 25m/s in 6 seconds. What is the acceleration of the car?

……………… (3)

5. Give two uses for visible light.

…………………………………………………………………………………………

………………………………………………………………………………………… (2)

Score [ /12]

Electromagnetic Induction – Science (Physics) 15

airglass

Learning Outcomes:

1. Describe the energy changes that take place in a generator.2. Explain how a generator induces a voltage. 3. Describe alterations that can be made to a generator to increase the voltage it

induces.

Generators

Key Ideas

1. The coil (or magnet) is rotated within a magnetic field (or coil)2. As it turns the coil cuts the magnetic field lines. 3. This induces a voltage (or current) in the coil. 4. The coil can then be connected to an existing circuit. 5. In a generator, energy is being converted from kinetic (mechanical) energy into

electrical energy. 6. The size of the induced voltage (or current) can be increased by:

a. Using a stronger magnetb. Having more turns in the coilc. Spinning/moving the coil (or magnet) faster.

Electromagnetic Induction – Science (Physics) 16

Model Answer: The Generator

Below is an example of an exam question on generators.

Attempt the question yourself first using the knowledge you have just gained. Make sure you use green pen to add any keyword that you have missed to make sure

you have a model answer.

1. Explain how a generator words. (3)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

2. Explain the effect in the inducted voltage when the following changes are made to a

generator

a. A stronger magnet is used. (2)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

b. The coil rotates fewer times per second. (2)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

What did you miss the first time around?

Electromagnetic Induction – Science (Physics) 17

Stretch Activity – Michael Faraday

Michael Faraday was the first person to observe how the size of an induced voltage depended upon the rate at which magnetic lines were cut.

But this was not all that he did! Use your laptop to research Michael Faraday and his contribution to Physics.

Note your findings below.

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

Electromagnetic Induction – Science (Physics) 18

Stretch Activity – Bicycles and Generating Electricity

Charities and companies all over the UK (e.g. WWF) run fundraising events to raise awareness on environmental issues. Many of these take the form of cycling events where participants take turns riding specially designed stationary bikes. These bikes are fitted with special devices which turn kinetic energy into electrical energy!

https://www.wwf.org.uk/events/cycling

Use your laptop to research answers to the following questions.

How do these bikes work? How much electrical energy can one person generate on the bike in 1 hour? Could this be a feasible way to generate energy globally?

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

Electromagnetic Induction – Science (Physics) 19

Electromagnetic Induction

Past Paper Questions

Q1. Photograph E shows a rechargeable torch.

Electromagnetic Induction – Science (Physics) 20

(a) When a student shakes the torch, the magnet moves through the coil and back again.This induces a voltage across the ends of the coil.The voltage is used to provide current to recharge the battery.

(i) Explain why a voltage is induced.

(2)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(ii) State one way to increase this voltage.

(1)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(b) Photograph F shows the components inside the torch.

Electromagnetic Induction – Science (Physics) 21

The torch uses a light-emitting diode (LED) to provide light.(i) When the LED is on, it shows that

(1)

   A    the current is alternating

   B    the torch is switched off

   C    there is a current in the circuit

   D    there is a fault in the circuit

(ii) The manufacturer of the torch states, "An LED is a more efficient source of light

than a filament lamp."

Explain this statement in terms of energy transfer.

(2)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(Total for question = 6 marks)

Electromagnetic Induction – Science (Physics) 22

Q2.

The diagram shows a magnet held above a coil. The coil is connected to a voltmeter.

(a) The magnet is released and falls into the coil.(i) Explain why the voltmeter shows a reading.

(2)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(ii) The magnet is released from a greater height.

How does this affect the voltmeter?

Explain your answer.

(2)

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(b) State how the voltmeter reading changes when the same magnet(i) moves more slowly into the coil

(1)      ..............................................................................................................................................

(ii) moves into a coil with more turns(1)

      ..............................................................................................................................................

(iii) is reversed so that the S-pole enters the coil first.(1)

      .............................................................................................................................................. 

(Total for question = 7 marks)

Electromagnetic Induction – Science (Physics) 23

Q3.

Some students are investigating a simple electric motor.

(a) When the switch is closed the coil spins on the axle.State why.

(2)      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(b) State two changes that would make the motor spin faster.

(2)1 .....................................................................................................................................................

      ..............................................................................................................................................

2 .....................................................................................................................................................

      ..............................................................................................................................................

Electromagnetic Induction – Science (Physics) 24

(c) The students change their circuit, replacing the cell and switch with a lamp.

When they spin the coil by hand, the lamp lights.Explain why the lamp lights.

(2)      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

      ..............................................................................................................................................

(Total for question = 6 marks)

Electromagnetic Induction – Science (Physics) 25

Electromagnetic Induction

Spec Point Notes

Magnetism and Electromagnetism Specification Notes

6.01 use the following units: ampere (A), volt (V) and watt (W)

Electromagnetic Induction – Science (Physics) 26

6.02 know that magnets repel and attract other magnets and attract magnetic substances

6.04 understand the term magnetic field line

Around every magnet there is a region of space where we can detect magnetism (where magnetic materials will be affected).

This is called the magnetic field and in a diagram we represent this with magnetic field lines.

The magnetic field lines should always point from north to south.

6.07 describe how to use two permanent magnets to produce a uniform magnetic field

pattern

A uniform magnetic field is comprised of straight, parallel lines which are evenly spaced.

Electromagnetic Induction – Science (Physics) 27

6.15 know that a voltage is induced in a conductor or a coil when it moves through a magnetic field or when a magnetic field changes through it and describe the factors that affect the size of the induced voltage

Coil is rotated within a magnetic field As it turns the coil cuts the magnetic field lines. This induces a voltage (or current) in the coil. This can then be connected to an existing circuit. In a generator, energy is being converted from kinetic (mechanical) energy into electrical

energy. The size of the induced voltage (or current) can be increased by:

o Using a stronger magneto Having more turns in the coilo Spinning/moving the coil faster.

6.16 describe the generation of electricity by the rotation of a magnet within a coil of wire and of a coil of wire within a magnetic field, and describe the factors that affect the size of the induced voltage

Magnet is rotated with a coil As it turns the coil cuts the constantly changing magnetic field lines from the magnet. This induces a voltage (or current) in the coil. This can then be connected to an existing circuit. In a generator, energy is being converted from kinetic (mechanical) energy into electrical

energy. The size of the induced voltage (or current) can be increased by:

o Using a stronger magneto Having more turns in the coilo Spinning/moving the magnet faster.

Electromagnetic Induction – Science (Physics) 28

Electromagnetic Induction – Science (Physics) 29