4. Electricity and magnetism
A section of Physics, 0625
Listing 10 of 2294 questions
A student plans to demonstrate the induction of an electromotive force (e.m.f.) in a wire. He has a length of wire, a sensitive centre‑reading galvanometer and a permanent magnet. Describe how the student uses the equipment. State two ways in which the student can increase the size of the induced e.m.f. shows a d.c. motor. magnet coil rotation of coil battery current – + On , draw an arrow between the poles of the magnet to show the direction of the magnetic field. State two ways of making the coil spin faster. State one way of making the coil spin in the opposite direction.
0625_w21_qp_31
THEORY
2021
Paper 3, Variant 1
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shows a horizontal, flat coil in a magnetic field N S A B coil axis The coil is connected to a cell. The coil rotates. Determine the direction of movement of the side AB relative to the plane of the coil. direction of movement = Explain how you determined the direction in . State and explain what happens to the coil as it reaches the vertical position. To operate as a motor, a split‑ring commutator and brushes are added to the parts shown in . Explain the effects of the split‑ring commutator and the brushes on the action of the motor.
0625_m23_qp_42
THEORY
2023
Paper 4, Variant 2
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is a sketch of some apparatus, found in a Science museum, which was once used to show how electrical energy can be converted into kinetic energy. When the switch is closed the wheel starts to turn. S N S N metal supports switch + – d.c. supply metal spoked wheel small dish of mercury magnet magnet wood base Explain why the wheel turns when the switch is closed. On , draw an arrow to show the direction of rotation of the wheel. Examiner’s Use The d.c. motor is another way to convert electrical energy into kinetic energy. In the space below, draw a labelled diagram of a d.c. motor. Describe how the split-ring commutator on an electric motor works.
0625_s07_qp_3
THEORY
2007
Paper 3, Variant 0
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A simple motor is made in a school laboratory. A coil of wire is mounted on an axle between the poles of a horseshoe magnet, as illustrated in . battery + – springy contacts coil B C D A N S At the instant illustrated in , the coil ABCD is horizontal and the battery is connected as shown. For this position, state the direction of the force on AB and the direction of the motion of AB. force on AB direction of motion of AB Explain why BC does not contribute to the turning force on the coil. At the instant when the coil is vertical, the springy contacts do not, in fact, make contact with the ends of the coil. Describe and explain what happens to the coil. The motor in does not rotate very quickly. The designer of a commercial motor is required to produce a faster-rotating motor. Suggest one change that could be made to increase the speed of the motor.
0625_s11_qp_31
THEORY
2011
Paper 3, Variant 1
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