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4.5 Electromagnetic effects

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Question 195

A small electric fan is powered by a simple d.c. motor. Which of the following modifications will decrease the speed of rotation of the fan?

A

Replace the permanent magnets in the motor with stronger ones.

B

Increase the voltage of the d.c. power supply.

C

Decrease the number of turns of wire on the coil.

D

Insert a soft iron core into the center of the coil.

Markscheme

4.5 Electromagnetic effects Questions

  1. IGCSE
  2. /Physics
  3. /4.5 Electromagnetic effects

275 exam-style questions on CIE IGCSE Physics 4.5 Electromagnetic effects, covering 4.5.1a Electromagnetic induction, 4.5.1b Direction of an induced e.m.f., 4.5.2 The a.c. generator, 4.5.3a Magnetic effect of a current and its applications, 4.5.3b Strength and direction of the field around wires and solenoids, 4.5.4a Force on a current-carrying conductor, 4.5.4b Force on beams of charged particles, 4.5.5 The d.c. motor, 4.5.6a Construction and operation of a transformer, 4.5.6b Turns ratio and current in a transformer, and 4.5.6c High-voltage transmission of electricity. Each one has a worked solution and a mark scheme showing where the marks go.

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