OCR P3.6,7 Electric motor, generators and transformers

Eve is investigating the force on a current-carrying wire when it is placed in a magnetic field, as shown in the figure.

The direction of the current in the wire is from left to right.

The magnetic field of the magnet is in the plane of the paper and perpendicular to the current carrying wire.

The current-carrying wire moves.

Use Fleming’s left-hand rule to predict the direction in which the wire moves.

• Up along the plane of the paper.

• Down along the plane of the paper.

• Out of plane of paper.

• Into the plane of paper.

Eve is investigating the force on a current-carrying wire when it is placed in a magnetic field, as shown in the figure.

Describe how you used Fleming’s left-hand rule to find the direction in which the wire moves.

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Eve is investigating the force on a current-carrying wire when it is placed in a magnetic field, as shown in the figure.

Explain why the current-carrying wire moves.

Use ideas about magnetic fields in your answer.

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Eve is investigating the force on a current-carrying wire when it is placed in a magnetic field, as shown in the figure.

The current in the wire is 2.0 A. The magnetic flux density is 0.060 T.

Calculate the force acting on the 4.5 cm length of the wire.

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Eve is investigating the force on a current-carrying wire when it is placed in a magnetic field, as shown in the figure.

The current in the wire is 2.0 A. The magnetic flux density is 0.060 T.

Explain what happens to the size of the force in when the current in the wire is doubled.

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Eve is investigating electromagnetic induction using two coils of wire that are placed close together.

Coil 1 is connected to a cell and a switch.

Coil 2 is connected to a zero-centre ammeter, which can show zero, positive or negative current flowing.

Eve's observations are shown in the diagrams below.

Explain why negative current flows in Coil 2 when the switch is closed.

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Eve is investigating electromagnetic induction using two coils of wire that are placed close together.

Coil 1 is connected to a cell and a switch.

Coil 2 is connected to a zero-centre ammeter, which can show zero, positive or negative current flowing.

Explain why no current flows in Coil 2, a few seconds after the switch is closed.

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The figure shows an alternating current (a.c.) generator being used to power a bulb.

The bulb flashes on and off.

As the coil passes through the vertical position the bulb is off.

Explain why.

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The figure shows an alternating current (a.c.) generator being used to power a bulb.

The coil is rotated at a faster speed.

Suggest two changes this will have on the bulb.

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The figure shows an alternating current (a.c.) generator being used to power a bulb.

The slip rings shown in Fig. 9.1 are replaced by a split-ring commutator.

Which graph shows the potential difference that will now be generated across the bulb?

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