Question

Two charges +10 pC and +20 pC are placed at a separation of 2 cm, then the electric potential due to the pair at the middle point of the line joining the two charges is_____.

• A. 9 V
• B. 18 V
• C. 27 V
• D. 13.5 V

Answer 1

The correct option is C 27 V

(c)
Using the equation, $V=\frac{Q}{4\pi {ϵ}_{0}r}$

the potential due to +10 pC is
$V_1=\frac{(10\times {10}^{-12}C)\times (9\times {10}^9)}{1\times {10}^{-2}m}=9V$

The potential due to +20 pC is

$V_2=\frac{(20\times {10}^{-12}C)\times (9\times {10}^9)}{1\times {10}^{-2}m}=18V$

The net potential at the given point is
= 9V + 18V = 27 V