A transformer is used to light a 100 ~W , 110 ~V lamp from a 220 ~V supply. If the supply current is 0.6 ~A , then the efficiency of the transformer is

Step-by-step solution

For a transformer, Input voltage, V₁=220 ~V Input current, I ₁=0.6 ~A Output power, P₂=100 ~W From, input power, P₁=V₁ I₁ aligned &=220 0.6 &=132 ~W aligned We know that, efficiency of transformer, aligned &= P₂ P₁ = 100 132 =0.7576 &=75.76 % 76 % aligned