Transformer doubt...

A step down transformer reduces 220V to 11V. the primary draws 5amp. of current and the secondary supplies 90amp. The efficiency of transformer is:

1) 20% 2)44% 3) 90% 4)100%

1 Answers

efficiency = Power outputPower intput

= (90 x 11)(220 x 5)

= 0.9

Hence (3) is correct

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