Question

An electric charge of $ 8.85\times 10^{-13}C $ is placed at the centre of a sphere of radius $ 1\,m $ . The electric flux through the sphere is

• A. $ 0.2\,\,NC^{-1}\,m^{2} $
• B. $ 0.1\,\,NC^{-1}\,m^{2} $
• C. $ 0.3\,\,NC^{-1}\,m^{2} $
• D. $ 0.01\,\,NC^{-1}\,m^{2} $

Answer 1

Answer: (B)

Electric flux, $\phi=E . A$
$\phi=\frac{1}{4 \pi \varepsilon_{0}} \times \frac{q}{r^{2}} \cdot 4 \pi r^{2}=\frac{4 \pi q}{4 \pi \varepsilon_{0}} $
$=9 \times 10^{9} \times 8.85 \times 10^{-13} \times 4 \times \frac{22}{7} $
$=0.1 \,N C^{-1} m^{2}$