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InterviewSolution
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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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Answer» Correct Answer - C The efficiency of transformer `=("Energy obtained from the secondary coil")/("Energy given to the primary coil")` or `eta=("Output power")/("Input power")` or `eta=(V_(s)I_(s))/(V_(p)I_(p))` Given, `V_(s)I_(s)=100W,V_(p)=220V,I_(p)=0.5A` Hence, `eta=(100)/(220xx0.5)=0.90=90%` Note The efficiency of an ideal transformer is 1 (or 100%). But in practice due to loss in energy, the efficiency of trensformer is always less than 1 (or less than 100%) |
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