The Motor Effect (AQA GCSE Combined Science: Trilogy: Physics): Exam Questions

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

Figure 1

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

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

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

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

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

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

Figure 2

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

What is the name given to this effect?

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

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

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Explain why this force acts on the wire.

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

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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

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.

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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).

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

Figure 4

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

Explain why.

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Describe three changes that would make the coil spin faster.

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

Figure 6 below shows an electric bell.

Figure 6

When the switch is closed, the bell rings continuously.

Explain why.

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

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Figure 1 shows a device known as a current balance.

Figure 1

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

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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

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: ....................................