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Free Electromagnetic Induction MCQs with Answers

288 Electromagnetic Induction MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Changing magnetic flux induces an emf according to Faraday's law, while Lenz's law gives the direction that opposes the change producing it. Transformers apply induction between coils to step alternating voltage up or down, with turns ratio, current transformation and energy losses determining practical operation.

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Faraday's LawLenz's LawTransformers
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288 questions · page 15 of 15

281. A setup transformer is that which :

  • A. Increase of power
  • B. Increase of current
  • C. Increase of voltage
  • D. Increase of energy

Explanation: A step-up transformer is a type of transformer that increases the voltage of an alternating current (AC) while decreasing the current.

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Correct answer: Increase of voltage

282. The inductance of solenoid depends upon the:

  • A. Area of cross section
  • B. Length of solenoid
  • C. Number of turns
  • D. All of above

Explanation: Therefore, the correct option is "All of the above" as the inductance of a solenoid depends on the area of cross section, the length of…

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Correct answer: All of above

283. A transformer changes 12V to 18000V and there are 6000 turns in secondary coil. The number of turns in primary coil are:

  • A. 40
  • B. 20
  • C. 30
  • D. 4

Explanation: 4: If there are 4 turns in the primary coil, the voltage transformation ratio would be 6000/4 = 1500, which matches the given…

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Correct answer: 4

284. An ideal transformer steps up or steps down:

  • A. Energy
  • B. AC voltage
  • C. DC voltage
  • D. Power

Explanation: An ideal transformer steps up or steps down AC voltage using the principle of electromagnetic induction.

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Correct answer: AC voltage

285. A step-up transformer is one that:

  • A. Increase the power
  • B. Increase the voltage
  • C. Increase the energy

Explanation: A step-up transformer is a transformer that increases the voltage from the primary coil to the secondary coil.

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Correct answer: Increase the voltage

286. The efficiency of a transformer which draws a power of 20 watt is 60%, the power supplied by it is:

  • A. 5 W
  • B. 1.2 W
  • C. 6 W
  • D. 12 W

Explanation: The formula for efficiency is:% Efficiency = (Total Power Output/Total Power Input) x 100So if power input is 20 W, and % Efficiency is…

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Correct answer: 12 W

287. A transformer steps down a given voltage Isom 220V to 55V. If current in primary coil is 4mA, then current in secondary coil will be:

  • A. 16mA
  • B. 2mA
  • C. 8mA
  • D. 4mA

Explanation: When a transformer steps down the voltage, it increases the current. In this case, since the voltage is stepped down from 220V to 55V, and…

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Correct answer: 16mA

288. A step down transformer:

  • A. Increases the output current
  • B. Increases the output power
  • C. Increases the output voltage
  • D. Decreases the output power

Explanation: Actually, a step-down transformer decreases the output current while increasing the output voltage.

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Correct answer: Increases the output voltage
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