Test: Electrostatic Potential & Potential due to a Point Charge (NCERT) - NEET MCQ

Work done by the electrostatic force is independent of the path followed by it, and it depends only on the initial and final positions. For example, work done in moving a unit positive charge in a closed loop of an electric field is zero.

Volt is the electrical unit of potential difference or voltage, and is expressed as V. One Volt is described as one joule of energy consumption per one coulomb electric charge.

Electric potential at a point in an electric field is defined as the work done in bringing a unit positive charge from infinity to that point.
Or,  V = W/q ​
Since charge is of magnitude unity, Hence electric potential at that point will be equal to the workdone ∴ ϕ = W

Here, q = 5 × 10(−7) C, r = 10 cm = 0.1 m

Work done, W = q(V_f − V_i) = 4 × 10⁻⁹ × 4.5 × 10⁴ = 1.8 × 10⁻⁴ J

Electric field of a point charge.

Electric potential of a point charge,

The distance PQ is r = V/E = 12/24 = 0.5 m
∴ Magnitude of charge
q' = 4πε₀Vr

= 10⁻⁹ C

The electric potential due to charge Q is

where r is the distance of observation point from the charge. At the same point, electric field is

Combining Eqs. (i) and (ii), we have

= 4πε₀Q × 10²² V/m^-1

Here, q = 2 μC = 2 × 10⁻⁶ C,
r_A = 2m, r_B = 1m

= −9 × 10³  V

Potential at point A is 
Potential at point B is
Work done in taking a charge Q from A to B is,

Work done is equal to zero because the potential of A and B are the same


No work is done if a particle does not change its potential energy
i. e. initial potential energy = final potential energy.