Physics-
General
Easy
Question
A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately
- 30%
- 50%
- 90%
- 10%
The correct answer is: 90%
The efficiency of transformer
or
or
Given,
Hence,
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