Question

Two charges of 4 microcoulomb and 16 microcoulomb are separated by a distance of 30 cm calculate the distance from the point from the smallest where the electric field intensity will be zero.at

Answer 1

 Dear user,


Two charges  and  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.

Ans: There are two charges,





Distance between the two charges, d = 16 cm = 0.16 m

Consider a point P on the line joining the two charges, as shown in the given figure.



r = Distance of point P from charge q1

Let the electric potential (V) at point P be zero.

Potential at point P is the sum of potentials caused by charges q1 and q2 respectively.



Where,

 = Permittivity of free space

For V = 0, equation (i) reduces to

 











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



Suppose point P is outside the system of two charges at a distance s from the negative charge, where potential is zero, as shown in the following figure.

For this arrangement, potential is given by,



For V = 0, equation (ii) reduces to













Therefore, the potential is zero at a distance of 40 cm from the positive charge outside the system of charges.

Hope it will be useful for u..