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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38 questions · page 2 of 2
- A. To reduce eddy currents
- B. To improve the flux linkage between the primary and secondary coils
- C. To dissipate the heat generated by the two coils
- D. To eliminate the back e.m.f produced in the secondary coils
Explanation: The primary coil and the secondary coil are wound on the soft iron core.
Correct answer: To improve the flux linkage between the primary and secondary coils- A. AC generator
- B. Motor
- C. Transformer
- D. DC generator
Explanation: A transformer is a device which increases or decreases alternating voltage through mutual induction.
Correct answer: Transformer- A. Half wave rectification
- B. Self-induction
- C. Mutual induction
- D. Full wave rectification
Explanation: The transformer works on the principle of Faraday's law of electromagnetic induction and mutual induction.
Correct answer: Mutual induction- A. 150
- B. 160
- C. 170
- D. 200
Explanation: As given,Vp = 200V, Vs = 50V, Ns = 40According to the transformer equation, Np/Ns = Vp/Vs Or, Np = Ns.Vp/VsPutting values, Np = (40 x 200)…
Correct answer: 160- A. Equal to (=)
- B. Less than (<)
- C. Greater than(>)
- D. Not equal
Explanation: In a step-down voltage, we decrease the voltage from the primary to the secondary voltage.
Correct answer: Less than (<)- A. Is reduced
- B. Is increased
- C. Remains same
- D. None of these
Explanation: A transformer essentially converts between voltage and current using a magnetic field, a step down transformer, steps down the input…
Correct answer: Is increased- A. By increasing the turn ratio
- B. By decreasing the turn ratio
- C. By minimizing Eddy currents
- D. By selecting core materials with a large hysteresis area
Explanation: Explanation:This option is correct because the flow of Eddy currents in the core of the transformer results in power loses due to heat.
Correct answer: By minimizing Eddy currents- A. Magnetic, electrically
- B. Electrical, magnetically
- C. Magnetic, magnetically
- D. Electrical, optically
Explanation: In a transformer, there is no electrical connection between the two coils, which are typically referred to as the primary and secondary…
Correct answer: Electrical, magnetically- A. Power input is equal to Power output.
- B. Power input is less than half of the power output.
- C. Power input is greater than Power output
- D. Power input is more than half of the power output.
Explanation: A is Correct, as an ideal transformer operates with 100% efficiency, meaning no energy is lost
Correct answer: Power input is equal to Power output.- A. Transformer
- B. Generator
- C. Galvanometer
- D. Avometer
Explanation: A transformer is the most common application of mutual induction that uses this phenomenon to change the values of alternating voltages…
Correct answer: Transformer- 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.
Correct answer: Increase of voltage- 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…
Correct answer: All of above- 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…
Correct answer: 4- 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.
Correct answer: AC voltage- 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.
Correct answer: Increase the voltage36. 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…
Correct answer: 12 W- 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…
Correct answer: 16mA- 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.
Correct answer: Increases the output voltage