Question

A point charge of + 1 nC is placed in space with permittivity of $8.85\times {10}^{-12}F/m$ as shown in figure. The potential difference $V_{PQ}$ between two points P and Q at distances of 40 mm and 20 mm respectively from the point charge is

• A. 0.22 kV
• B. -225 V
• C. -2.24 kV
• D. 15 V

Answer 1

The correct option is B -225 V

Ans : (b)

$V_P-V_Q=\frac{q}{4\pi {ϵ}_0\left(OP\right)}-\frac{q}{4\pi {ϵ}_0\left(QP\right)}$
$=9\times {10}^9[\frac{{10}^{-9}}{40\times {10}^{-3}}-\frac{{10}^{-9}}{20\times {10}^{-3}}]$
$=-225$volts