Question

We know that first step for solving this problem is to find the resistance of each bulb. So calculate the resistance of both bulbs rated 100W at 220V and 60W at 220V respectively.

• A. $\frac{(220{)}^2}{100}$, $\frac{(220{)}^2}{60}$
• B. $\frac{(220{)}^2}{60}$, $\frac{(220{)}^2}{100}$
• C. $\frac{220}{100}$, $\frac{220}{60}$
• D. $\frac{220}{60}$, $\frac{220}{100}$

Answer 1

The correct option is A $\frac{(220{)}^2}{100}$, $\frac{(220{)}^2}{60}$

As we know that,
$P=\frac{V^2}{R}$
$⟹R=\frac{V^2}{P}$
For first bulb, Let's say $R_1$
$\therefore R_1=\frac{(220{)}^2}{100}$
and For second bulb, Let's say $R_2$
$R_2=\frac{(220{)}^2}{60}$