Question

Two bulbs of 500 W and 200 W are manufactured to operate on 220 V line. The ratio of heat produced in 500 W and 200 W, in two cases, when firstly they are connected in parallel and secondary in series will be

• A. $\frac{5}{2}:\frac{2}{5}$
• B. $\frac{5}{2}:\frac{5}{2}$
• C. $\frac{2}{5}:\frac{5}{2}$
• D. $\frac{2}{5}:\frac{2}{5}$

Answer 1

The correct option is A $\frac{5}{2}:\frac{2}{5}$

In parallel, $\frac{H_1}{H_2}=\frac{P_{1}t}{P_{2}t}=\frac{P_1}{P_2}=\frac{500}{200}=\frac{5}{2}$

In series, $\frac{H_1}{H_2}=\frac{I^2{R}_{1}t}{I^2{R}_{2}t}=\frac{R_1}{R_2}=\frac{v^2/P_1}{V^2/P_2}=\frac{P_2}{P_1}=\frac{200}{500}=\frac{2}{5}$