If a cube of side 5 cm has a charge of 6 microcoulombs , then the surface charge density is

Q: If a cube of side 5 cm has a charge of 6 microcoulombs, then the surface charge density is:

(a) 4 × 102  μC/m2

(b) 4 × 102  C/m2

(c) 4 × 103  μC/m2

(d) 4 × 103  C/m2

Ans: (a)

Sol: Surface charge density , $\large \sigma = \frac{Charge}{Surface \; area}$

$\large \sigma = \frac{6 \mu C}{6 \times (5 \times 10^{-2})^2}$

= 4 × 102  μC/m2