Two charges 5 × 10 –8 C and –3 × 10 –8 C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.

Question

Philoid · Accepted Answer

Given,

Two charges q_A = 5 x 10^-8 C and q_B = -3x10^-8 C

Distance between two charges, r = 16 cm = 0.16 m

Consider a point O on the line joining two charges where the electric potential is zero due to two charges.

From the figure we can see that, x = distance of point O from charge q_A

Electric potential at point O due to q_A,

ϵ₀ is the permittivity of free space. Its value is 8.85 x 10^-12 F/m

Electric potential at point O due to q_B

Since the total electric potential at O is zero,

⇒ V_A + V_B = 0

⇒

On cross multiplying we get,

5 × (0.16 -x) = 3x

⇒ 0.8 – 5x = 3x

⇒ 8x = 0.8

⇒x = 0.1 m = 10 cm(from charge q_A)

∴ at a distance of 10 cm from the positive charge, the potential is zero between the two charges.

Two charges 5 × 10–8 C and –3 × 10–8 C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.

Two charges 5 × 10^–8 C and –3 × 10^–8 C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.