Question 901: Electrostats & Capacitance

Question

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: The potential (V) at any axial point, at $$2 \mathrm{~m}$$ distance $$(r)$$ from the centre of the dipole of dipole moment vector $$\vec{P}$$ of magnitude, $$4 	imes 10^{-6} \mathrm{C} \mathrm{m}$$, is $$\pm 9 	imes 10^3 \mathrm{~V}$$.
(Take $$\frac{1}{4 \pi \epsilon_0}=9 	imes 10^9 \mathrm{SI}$$ units)
Reason R: $$V= \pm \frac{2 P}{4 \pi \epsilon_0 r^2}$$, where $$r$$ is the distance of any axial point, situated at $$2 \mathrm{~m}$$ from the centre of the dipole.
In the light of the above statements, choose the correct answer from the options given below:

Accepted Answer

The potential $$V$$ at any point, at distance $$r$$ from centre of dipole $$=\frac{K P \cos 	heta}{r^2}$$
At axial point where $$	heta=0^{\circ}, V=\frac{K P}{r^2}=\frac{9 	imes 10^9 	imes 4 	imes 10^{-6}}{2^2}=9 	imes 10^3 \mathrm{~V}$$
At axial point where $$	heta=180^{\circ}, V=\frac{-K P}{r^2}=-9 	imes 10^3 \mathrm{~V}$$

Answer

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

Answer

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

Answer

A is true but R is false.

Answer

A is false but R is true.

Electrostats & Capacitance

Choose the correct answer: