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

Options

A. 0.95
B. 0.99
C. 0.9
D. 0.96

Answer

C

Explanation

The efficiency of the transformer is
` eta = ("Output power "(P_(out)))/("Input power"(P_("in")))xx100`
Here ,
`P_("out") = 100 W `
`P _("in") = (220V ) (0.5 A ) = 11 0 W `
` :. " " eta = (100 W)/(110W) xx 100 approx 90 % `