Question

A cube has point charges of magnitude $-q$ at all its vertices. Electric field at the centre of the cube is:

• A. $\frac{1}{4 \pi \varepsilon_{0}} \frac{6 q}{3 a^{2}}$
• B. $\frac{1}{4 \pi \varepsilon_{0}} \frac{8 q}{a^{2}}$
• C. zero
• D. $\frac{1}{4 \pi \varepsilon_{0}} \frac{-8 q}{a^{2}}$

Answer 1

Answer: (C)

Clearly, the electric-field of each point charge is equal and opposite to the electric-field of charge diagonally opposite to it. So, the net electric field at centre of the cube is zero.