Question

A transformer is used to light 140 watt 24 volt lamp from 240 volt AC mains; the current in the main cable is 0.7 amp. The efficiency of the
transformer is :​

Answer 1

Answer:

Mains voltage is 240V and mains current is 0.7amp so inpur power will be 240×0.7=168watt

But output power is given as 140 Watt so efficinecy=(output/input)×100 % =83.33 %

Answer 2

Answer:

Mains voltage is 240V and mains current is 0.7amp so inpur power will be 240×0.7=168watt

But output power  is given as 140 Watt so efficinecy=(output/input)×100  %  =83.33 % .