Question

Assertion A: The potential (V) at any axial point, at 2 m distance (r) from the centre of the dipole of dipole moment vector of magnitude, 4 × 10⁻⁶ Cm, is ± 9 × 10³ V. (Take = 9 × 10⁹ SI units) 

Reason R: where r is the distance of any axial point, situated at 2 m from the centre of the dipole.

In the light of the above statements, choose the correct answer from the options given below:

Options

• Both A and R are true and R is the correct explanation of A.

• Both A and Rare true and R is NOT the correct explanation of A.

• A is true but R is false.

• A is false but R is true.

Answer 1

A is true but R is false.

Explanation:

Let us analyse both the statement and the reason.

The potential V at any point, at distance r from the centre of the dipole = `(KP cos^Phi)/r^2`

At axial point where Φ = 0°,

V = `(KP)/r^2`

= `(9 xx 10^9 xx 4 xx 10^-6)/2^2`

= 9 × 10³ V

At the axial point where Φ = 180°,

V = `(- KP)/r^2`

= 9 × 10³ V

Hence, A is true, but R is false.