Free Transformers MCQs with Answers
38 Transformers MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Transformers transfer alternating electrical energy between coils by mutual induction, with voltage ratio determined by the turns ratio. The topic covers step-up and step-down transformers, current changes, ideal power conservation and practical losses such as heating and flux leakage. A transformer requires changing magnetic flux, so it does not operate with steady direct current.
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- A. self induction only
- B. mutual induction between two coils linked by a common changing flux
- C. electrostatic attraction
- D. the motor effect
Explanation: Alternating current in the primary produces a continuously changing flux, which the laminated iron core carries to the secondary, where it…
Correct answer: mutual induction between two coils linked by a common changing flux- A. more turns on the secondary than the primary
- B. fewer turns on the secondary than the primary, giving a lower output voltage
- C. the same number of turns on both
- D. no core
Explanation: Voltage divides in the ratio of the turns, so fewer secondary turns give a lower voltage, and for an ideal transformer the current rises…
Correct answer: fewer turns on the secondary than the primary, giving a lower output voltage- A. 2200 V
- B. 22 V
- C. 220 V
- D. 2.2 V
Explanation: The turns ratio is 10 to 1 down, so the voltage falls by the same factor, from 220 V to 22 V.
Correct answer: 22 V- A. high voltage travels faster
- B. the current is then small, so the I squared R heating loss in the cables is small
- C. high voltage cables are cheaper
- D. consumers need high voltage
Explanation: For a given power, raising the voltage lowers the current in proportion, and since the loss goes as the square of the current, a tenfold…
Correct answer: the current is then small, so the I squared R heating loss in the cables is small- A. make it lighter
- B. increase the flux through it
- C. reduce energy lost as heat through eddy currents in the core
- D. insulate the two coils from each other
Explanation: Thin sheets separated by insulating varnish break up the circulating paths available to eddy currents, so much less energy is dissipated…
Correct answer: reduce energy lost as heat through eddy currents in the core- A. the output power equals the input power
- B. the output voltage equals the input voltage
- C. the output current equals the input current
- D. no flux passes through the core
Explanation: Ideal means lossless, so all the power delivered to the primary appears at the secondary, and voltage and current change in inverse…
Correct answer: the output power equals the input power- A. direct current is too dangerous
- B. steady direct current gives no changing flux, so no emf is induced in the secondary
- C. the core would melt
- D. direct current cannot flow in a coil
Explanation: Induction requires a changing flux, and a steady current produces a steady flux, so the secondary voltage is zero except at the instants…
Correct answer: steady direct current gives no changing flux, so no emf is induced in the secondary- A. Doubles
- B. Halves
- C. Remains the same
- D. Becomes four times
Explanation: With the turns ratio fixed, doubling the primary voltage doubles the secondary voltage, and for a given load resistance the secondary…
Correct answer: Doubles- A. Eddy currents
- B. Hysteresis
- C. Resistance in winding
- D. None of these
Explanation: An alternating magnetic flux in the iron core induces circulating currents within the core itself.
Correct answer: Eddy currents- A. Zero
- B. 1
- C. More than 1
- D. Infinite
Explanation: The coupling coefficient (k) is a measure of how efficiently magnetic flux is transferred between two coils.
Correct answer: 1- A. Step up
- B. Step down
- C. Equalize
- D. None of these options is correct
Explanation: The purpose of the transformer is to step down the AC voltage from the mains supply and feed it to the rectifier.
Correct answer: Step down- A. Voltage
- B. Current
- C. Power
- D. Capacitance
Explanation: A transformer changes voltages and current but the power remains constant.
Correct answer: Power- A. Increase voltage reduce current
- B. Increase current, reduce voltage
- C. Increase both voltage and current
- D. Increase both voltage and power
Explanation: Step-up transformers are used in long-distance electricity transmission to increase the voltage and decrease the current.
Correct answer: Increase voltage reduce current- A. current
- B. voltage
- C. resistance
- D. power
Explanation: The power remains constant. This means that the power input to the primary coil is equal to the power output from the secondary coil…
Correct answer: power- A. An ideal transformer
- B. A step-up transformer
- C. A step-down transformer
- D. An automatic transformer
Explanation: A step-down transformer is specifically designed to reduce voltage from a higher input (primary) to a lower output (secondary).
Correct answer: A step-down transformer- A. made up of iron metal.
- B. insulated from each other.
- C. separated with metallic laminations.
- D. separated with laminations having winding wires.
Explanation: Eddy currents are induced in the core of a transformer when there is a changing magnetic flux.
Correct answer: insulated from each other.- A. II only
- B. III only
- C. I and II
- D. I and III
Explanation: The correct answer is Option A: II only. In a transformer, the output voltage is typically greater than the input voltage due to the…
Correct answer: II only- A. I and II.
- B. I and IV.
- C. II and III.
- D. III or IV.
Explanation: A transformer is an electrical device used to transfer electrical energy between two or more circuits through electromagnetic induction.
Correct answer: III or IV.- A. Be zero.
- B. Increase.
- C. Decrease.
- D. Be undetermined.
Explanation: In a transformer, the induced electromotive force (e.m.f.) in the secondary coil is generated by the changing magnetic field created by…
Correct answer: Be zero.- A. Soft iron
- B. Copper
- C. Nickel
- D. Aluminium
Explanation: The core of a transformer is made of soft iron because it has high permeability so ,it provides complete linkage of magnetic flux of the…
Correct answer: Soft ironTransformers MCQs: common questions
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