A $12 \mathrm{~V}, 60 \mathrm{~W}$ lamp is connected to the secondary of a step down transformer, wh

Question

A $12 \mathrm{~V}, 60 \mathrm{~W}$ lamp is connected to the secondary of a step down transformer, whose primary is connected to ac mains of 220 V . Assuming the transformer to be ideal, what is the current in the primary winding?\

Professor PC Thomas Classes · Answer

(c) :\ Let current in the primary is $I_{p}$.\ As, the transformer is ideal\ $	herefore \quad P_{i}=P_{0}$\ $\Rightarrow \quad 220 	imes I_{p}=60$\ $\Rightarrow \quad I_{p}=\frac{60}{220}=\frac{6}{22}=\frac{3}{11}=0.27 \mathrm{~A}$\