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

Given: Output power P=VSIS=100 W Voltage across primary Vp=220 V Current in the primary Ip=0.5 A Voltage across secondary = 110 V Efficiency of a transformer η=( textoutputpower/ textInputpower)×100 η=(P/Vp Ip)×100 =(100/220×0.5)×100 =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

$30%$

$50%$

$90%$

$10%$

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%

Given : Output power P=VS​IS​=100W Voltage across primary Vp​=220V Current in the primary Ip​=0.5A Voltage across secondary =110V Efficiency of a transformer η=Inputpoweroutputpower​×100 η=Vp​Ip​P​×100 =220×0.5100​×100 =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

$30%$

$50%$

$90%$

$10%$