A transformer is used to light a 100 W and 110 V lamp from a 220 V mains. If the main current is 0.5 A, the efficiency of the transformer is approximately

Question

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

Tardigrade Admin · Accepted Answer

The efficiency of transformer =( text Energy obtained from the secondary coil / text Energy given to the primary coil ) or η=( text Output power / text Input power ) or η=(Vs Is/VP Ip) Given, Vs Is=100 W, Vp=220 V, Ip=0.5 A Hence, η=(100/220 × 0.5)=0.90=90 %

Q. A transformer is used to light a 100W and 110V lamp from a 220V mains. If the main current is 0.5A, the efficiency of the transformer is approximately

30%

50%

90%

10%

The efficiency of transformer = Energy given to the primary coil Energy obtained from the secondary coil ​ or η= Input power Output power ​ or η=VP​Ip​Vs​Is​​ Given, Vs​Is​=100W,Vp​=220V,Ip​=0.5A Hence, η=220×0.5100​=0.90=90%

Q. A transformer is used to light a $100 W$ and $110 V$ lamp from a $220 V$ mains. If the main current is $0.5 A$ , the efficiency of the transformer is approximately