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A step down transformer works on 220 vol...

A step down transformer works on 220 volts a.c. mains. It is used to light a 100 w, 20 V bulb. The main current is 0.5 A. What is the efficiency of the transformer?

A

`99.1%`

B

`90.91%`

C

`100%`

D

`9.091%`

Text Solution

Verified by Experts

The correct Answer is:
B
Input power, `P_(P)=I_(P)V_(P)=(0.5)(220)=110 W`
Output power, `P_(S)=100 W`
`therefore" Efficiency "=(100)/(110)=0.9091" or "90.91%`
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