The Motor Effect (AQA GCSE Physics)

Exam Questions

1 hour11 questions
1a3 marks

Figure 1 shows a coil (solenoid) wrapped around a plastic PVC pipe. A current flows in the coil in the direction of the arrow.

Figure 1

7-2-e-1a-pvcpipe-solenoid

On Figure 1, draw the magnetic field lines around the coil.

Add arrows to show the direction of the field.

1b1 mark

A long soft iron bar is placed inside the PVC pipe. State the name of the device when current flows in the coil.

1c2 marks

Current in a wire travels into the plane of the page, indicated by a cross in Figure 2.

Figure 2

screenshot-2023-03-13-at-17-18-54

Draw lines to represent the magnetic field generated by this current.

Did this page help you?

2a2 marks

Higher Only

The diagram in Figure 1 shows apparatus used to demonstrate the motor effect.

Figure 1

7-2-e-2a-motor-effect-demo-cell

Q is a piece of copper wire resting on two other wires. A current passes anticlockwise through the circuit.

Describe what happens to wire Q when the current is switched on.

2b1 mark

Higher Only

The direction of the magnetic field is reversed.

Describe any differences in the motion of Q.

2c1 mark

Higher Only

The current is increased.

Describe any differences in the motion of wire Q.

Did this page help you?

3a1 mark

Higher Only

The current and magnetic field cause the coil in Figure 1 to rotate. 

Figure 1

7-2-e-3a-motor7-23e-a

State the name of the phenomenon causing this rotation.

3b1 mark

Higher Only

Using Fleming's left hand rule, state the direction that the left side of the coil moves in Figure 1.

3c2 marks

Higher Only

A current of 2.5 A flows in the coil, which is 0.10 m long and 0.10 m wide.

If the magnetic flux density is 0.10 T, calculate the force on the left side of the coil.

Use your equation sheet.

   

   

Force = .................................... N

Did this page help you?

1a2 marks

Figure 1 below shows a straight current carrying wire. The current is coming out of the page.

Figure 1

q1a-7-2-medium-aqa-gcse-physics

Complete Figure 1 to show the pattern of magnetic field lines around the wire.

1b1 mark

How would the pattern change if the direction of the current was reversed?

1c3 marks

The picture below shows a long coil of wire called a solenoid.

q1c-7-1-medium-aqa-gcse-physics

When a current passes through the solenoid it produces a magnetic field.

Suggest three changes that would increase the strength of the magnetic field.

Did this page help you?

2a1 mark

Higher Only

Figure 2 below shows a straight wire passing between the poles of two magnets.

Figure 2

fig-2-7-1-medium-aqa-gcse-physics

When a current passes through the wire a force is exerted on the wire.

What is the name given to this effect?

2b4 marks

Higher Only

Describe how the direction of the force can be determined using Fleming’s Left-Hand Rule.

2c1 mark

Higher Only

Add an arrow to Figure 2, showing the direction of the force.

2d3 marks

Higher Only

Explain why this force acts on the wire.

2e3 marks

Higher Only

Suggest three changes that would increase the force acting on the wire.

Did this page help you?

3a4 marks

Higher Only

The apparatus shown in Figure 3 below can be used to measure the force acting on a current-carrying wire placed in a magnetic field.

Figure 3

fig-3-7-1-medium-aqa-gcse-physics

The balance is initially zeroed so that when the power supply is off, it shows no reading.

When the power supply is turned on, the balance shows a reading.

As the current is increased, the reading increases.

Explain in terms of forces why the reading increases.

3b4 marks

Higher Only

For the above apparatus, when the current in the wire was 0.25 A, a force of 1.96 mN was exerted on the wire

The length of wire between the poles of the magnet was 0.042 m

Calculate the magnetic flux density between the poles of the magnet.

Give your answer to 2 significant figures.

(You may need to look up the appropriate formula on the Physics Equations Sheet).

Did this page help you?

4a4 marks

Higher Only

Figure 4 below shows a simple d.c. motor.

Figure 4

fig-4-7-1-medium-aqa-gcse-physics

When a direct current is supplied to the coil, the coil starts to spin.

Explain why.

4b3 marks

Higher Only

Describe three changes that would make the coil spin faster.

4c2 marks

Higher Only

Describe two changes that could reverse the direction of the coil.

Did this page help you?

54 marks

Higher Only

Figure 5 below shows a loudspeaker.

Figure 5

fig-5-7-2-medium-aqa-gcse-physics

The loudspeaker produces a sound when an alternating current is connected to the coil.

Explain why.

Did this page help you?

1a4 marks

Figure 6 below shows an electric bell.

Figure 6

fig-6-7-1-medium-aqa-gcse-physics

When the switch is closed, the bell rings continuously.

Explain why.

1b2 marks

Higher Only

Explain what would happen if the batteries were inserted the wrong way around and the switch closed again.

Did this page help you?

2a4 marks

Higher Only

Figure 1 shows a device known as a current balance.

Figure 1

7-2-h-2a-current-balance

The switch is closed. Describe and explain the subsequent motion of the section of wire labelled A to B.

2b6 marks

Higher Only

A small mass of 0.080 kg is used and placed 3.0 cm from the metal support. 

The section of wire labelled A to B is 6.0 cm long and is placed 8.0 cm away from the metal support.

The system is in equilibrium after the switch has been closed. 

Assume the mass of the plastic and the mass of the wire are negligible.

   

Calculate the magnetic flux density at the location of wire section AB when a current of 0.2 A passes through it. 

Give your answer to Y significant figures.

Take the value of acceleration due to gravity to be 10 m/s2 for this question.

Use the Physics Equation Sheet. 

   

   

Magnetic flux density = .................................... T

Did this page help you?

3a5 marks

Higher Only

Figure 1 shows a wire passing between a North and South pole, with a flux density of 0.10 T between the poles.

The magnets cover 30 cm of the wire's length.

The wire has a resistance of 0.2 Ω and dissipates 5 J of energy every second. 

The current travels out of the plane of the page.

Figure 1

7-2-h-3a-loudspeaker

Calculate the magnitude of the force on the wire and state its direction.

Give your answer to 2 significant figures.   

   

Force (2 significant figures) = .................................... N
   
Direction: ....................................
3b4 marks

Higher Only

Figure 2 shows a diagram of a loudspeaker in a live music venue.

Figure 2

7-2-h-3b-loudspeaker

Explain why an alternating current in the coil causes the speaker cone to oscillate.

Did this page help you?