Question

If current in an electric bulb changes by 1%, then the power will change by

• A. 1%
• B. 2%
• C. 4%
• D. $\frac{1}{2}$%

Answer 1

Answer: (B)

2%

Answer 2

By using P = i²R ⇒ P ∝ i² ⇒ $\frac{\Delta P}{P} = 2\frac{\Delta i}{i}$ ⇒ change in power = 2%