A transformer is used to light a `100 W` and `110 V` lamp from a `220V` mains. If the main current is `0.5 A`, the Efficiency of the transformer is approximately:A. `30 %`B. `50 %`C. `90 %`D. `10 %`

A transformer is used to light a `100 W` and `110 V` lamp from a `220V

1.	A transformer is used to light a `100 W` and `110 V` lamp from a `220V` mains. If the main current is `0.5 A`, the Efficiency of the transformer is approximately:A. `30 %`B. `50 %`C. `90 %`D. `10 %`
Answer» Correct Answer - C The efficiency of transformer `=("Energy obtai n ed form the secondary coil")/("Energy given t o the primary coil")` or `eta=("Output power")/("Input power")` or `eta=(V_(s)I_(s))/(V_(p)I_(p))` Given, `V_(s)I_(s)=100 W, V_(p)=200V, I_(p)=0.5 A` Hence, `eta=100/(220xx0.5) 0.90=90%`

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A transformer is used to light a `100 W` and `110 V` lamp from a `220V` mains. If the main current is `0.5 A`, the Efficiency of the transformer is approximately:A. `30 %`B. `50 %`C. `90 %`D. `10 %`

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