Question
A transforner 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 %
Solution
C.
90 %
The efficiencvy of transformer
Energy obtained from the secondary coil
__________________________________
Energy given to the primary coil
n = output
_______
Input
Given VsIs = 100 W, Vp = 220 V, IP = 0.5 A
Hence, n = 100 / 220 x 0.5 = 90 %
