Question

A charge of + 4μC is kept at a distance of 50 cm from a charge of – 6μC. Find the two points where the potential is zero

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

Answer 1

Answer: (A)

Internal point lies at a distance of 20 cm from 4μC charge and external point lies at a distance of 100 cm from 4μC charge.

Answer 2

For internal point X, $x_{1} = \frac{x}{\left( \frac{Q_{2}}{Q_{1}} + 1 \right)} = \frac{50}{\frac{6}{4} + 1} = 20cm$ and for external point Y, $x_{1} = \frac{x}{\left( \frac{Q_{2}}{Q_{1}} - 1 \right)} = \frac{50}{\frac{6}{4} - 1} = 100cm$