The motor effect and electric motors Quiz
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5 questions, one answer each
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1. What happens to the force on a current-carrying wire in a magnetic field if the wire is parallel to the field?
- A. It is at its maximum
- B. It is zero
- C. It reverses
- D. It doubles
2. In Fleming's left-hand rule the thumb shows the direction of:
- A. The current
- B. The field
- C. The force
- D. The voltage
3. What is the purpose of the split-ring commutator?
- A. To make the magnets stronger
- B. To increase the voltage
- C. To keep the coil cool
- D. To reverse the current in the coil every half turn
4. Which change would NOT make a d.c. motor turn faster?
- A. Using a larger current
- B. Using stronger magnets
- C. Reducing the current
- D. Adding more turns to the coil
5. What type of current makes the coil in a loudspeaker vibrate?
- A. A varying alternating current
- B. A steady direct current
- C. No current
- D. Only a current in the magnet