Question

Eight charges, $1 \mu C ,-7 \mu C ,-4 \mu C , 10 \mu C , 2 \mu C ,$ $-5 \mu C,-3 \mu C$ and $6 \mu C$ are situated at the eight corners of a cube of side $20 cm$. A spherical surface of radius $80 cm$ encloses this cube. The centre of the sphere coincides with the centre of the cube. Then the total outgoing flux from the spherical surface (in unit of volt meter) is :

• A. $36 \pi \times 10^{3}$
• B. $684 \pi \times 10^{3}$
• C. Zero
• D. None of the above

Answer 1

Answer: (C)

Total flux enclosed by surface $=\frac{Q_{\text {inclosed }}}{\varepsilon_{0}}$
$=\frac{1-7-4+10+2-5-3+6}{\varepsilon_{0}} \times 10^{-6}$
$=0$