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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. `63.8%`B. `74%`C. `83.3%`D. `48%` |
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Answer» Correct Answer - C Output power = 140 W Input power `= 240xx0.7=168 W` Efficiency `=("output power")/("input power")xx100=(140)/(168)xx100=83.3%` |
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