Question

two point charge of 5 ocoulomb and 20 coulomb are separated by a distance of 2 metre find the point on the line joining them at which electric field intensity is zero​

Answer 1

Solution:

Given,

q1 = 5 C

q2 = 20 C

Electric field at P is 0

Therefore, E1 = E2

Kq1/(2 - x)^2 = Kq2/x^2

q1x^2 = q2(2 - x)^2

3 × x^2 = 20 × (2 - x)^2 /4

x^2 = 4 (2 - x)^2

x^2 = [2 (2 - x)]^2

x = 2 (2 - x)

x = 4 - 2x

2x = 4

Hence, x = 2m

Thus, the point at which electric field is zero is at "2 metres " from 20 C.