Question

A charge of $+4\mu C$ is kept at a distance of $50$ cm from a charge of $-6\mu C$ . Find the two points where the potential is zero.

• A. Internal point lies at a distance of $20cm$ from $4\mu C$ charge and external point lies at a distance of $100cm$ from $4\mu C$ charge.
• B. Internal point lies at a distance of $30cm$ from $4\mu C$ charge and external point lies at a distance of $100cm$ from $4\mu C$ charge.
• C. Potential is zero only at $20cm$ from $4\mu C$ charge between the two charges
• D. Potential is zero only at $20cm$ from $-6\mu C$ charge between the two charges

Answer 1

Answer: (C)

The charges are given as,

$q_1=4\mu C$

$q_2=-6\mu C$

The potential at P is given as,

$0=k\frac{q_1}{r_1}+k\frac{q_2}{r_2}$

$0=k\frac{4}{x}+k\frac{\left(-6\right)}{0.5-x}$

$0=k\frac{4}{x}+k\frac{\left(-6\right)}{0.5-x}$

$x=0.2m$

Thus, potential is zero only at $20cm$ from $4\mu C$ charge between the two charges.