The DC Motor Quiz
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5 questions, one answer each
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1. What causes the turning effect on a current-carrying coil in a magnetic field?
- A. The two sides of the coil carry current in opposite directions and feel forces in opposite directions
- B. The coil heats up unevenly
- C. The magnetic field pushes the whole coil sideways
- D. The brushes spin the coil directly
2. Which of these will NOT increase the turning effect of a motor's coil?
- A. Increasing the current
- B. Increasing the number of turns
- C. Increasing the strength of the magnetic field
- D. Increasing the length of the brushes
3. What is the function of the split-ring commutator?
- A. To measure the current in the coil
- B. To reverse the current in the coil every half turn
- C. To increase the voltage supplied
- D. To keep the coil stationary
4. If the direction of the current in a motor's coil is reversed but the magnetic field stays the same, what happens to the direction of the force?
- A. It stays the same
- B. It reverses
- C. It becomes zero
- D. It doubles
5. A student reverses both the current and the magnetic field direction in a motor at the same time. What happens to the direction of the force on the coil?
- A. It reverses
- B. It stays the same
- C. It becomes zero
- D. It rotates by 90 degrees