The efficiency of a transformer which draws a power of 20 watt is 60%, the power supplied by it is:
Correct answer: D. 12 W
- 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 60% we can rearrange the formula to make Power Output the subject and get the answer 12 W.
Last updated
About Transformers
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.
Practise Electromagnetic Induction
288 free Electromagnetic Induction MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Exams that ask Physics questions like this
Physics is on 13 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.