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A transformer is used to light a 140 W, ...

A transformer is used to light a 140 W, 24 V lamp from 240 V AC mains. The current in mains cable is 0.7 A, find the efficiency of transformer.

A

0.638

B

0.74

C

0.833

D

0.48

Text Solution

Verified by Experts

The correct Answer is:
C
Out power = 140 watt
Input power ` = 240 xx 0.7 = 168 ` watt Efficiency = `140/168 xx 100 = 83.3%`
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