Question

When the power delivered by a $100$ volt battery is $40$ watts, the equivalent resistance of the circuit is:

• A. $100ohms$
• B. $250ohms$
• C. $300ohms$
• D. $350ohms$

Answer 1

The correct option is B $250ohms$

$P=\frac{V^2}{R}\Rightarrow R=\frac{V^2}{P}=\frac{100\times 100}{40}=250ohms$

Hence, option B is correct.