Question

A metal cube of side 5 cm is charged with 6 μC. The surface charge density on the cube is

• A. \(0.125 \times 10^{-3} \, \text{C} \, \text{m}^{-2}\)
• B. \(0.25 \times 10^{-3} \, \text{C} \, \text{m}^{-2}\)
• C. \(4 \times 10^{-3} \, \text{C} \, \text{m}^{-2}\)
• D. \(0.4 \times 10^{-3} \, \text{C} \, \text{m}^{-2}\)

Answer 1

The Correct Option is D

Surface charge density ($\sigma$) = $\frac{\text{Charge (Q)}}{\text{Surface Area (A)}}$

Side = 5 cm = 0.05 m.

A = 6 × side² = 6 × (0.05)² = 0.015 m² Q = 6 μC = 6 × 10^-6 C

$\sigma = \frac{6 \times 10^{-6} \text{ C}}{0.015 \text{ m}^2} = 0.4 \times 10^{-3} \text{ C m}^{-2}$