Two charges of `+- 0.2 mumuC` and `-0.2 mumuC` are placed `10^-6` cm apart. Calculate the electric field at an axial point at a distance of 10 cm from their mid point. Use the standard value of `epsilon_0`

Explanation

Here, `q = 0.2 mu mu C = 0.2 xx 10^(-12) C`
`2a = 10^(-6) cm = 10^(-8)m, r = 0.1 m`
and `1/(4 pi in_0) = 9 xx 10^9 Nm^(2) C^(-2)`
So, electric dipole moment `vecP = q(2a)`
`= 0.2 xx 10^(-12) xx 10^(-8) cm`
`= 0.2 xx 10^(-20) cm`
Electric intensity E at a point on axial line due to short dipole is
`E = 1/(4pi in_0) (2P)/(r^3)`
`= (9 xx 10^9 xx 2 xx 0.2 xx 10^(-20))/((0.1)^3)`
`= 3.6 xx 10^(-8) NC^(-1)`