The distance between charges $+q$ and $-q$ is $2l$ and between $+2q$ and $-2q$ is $4l$. The electrostatic potential at point $P$ at a distance $r$ from center $O$ is $-\alpha\left[\frac{ql}{r^2}\right]\times10^9\,V$, where the value of $\alpha$ is __________. (Use $\frac{1}{4\pi\varepsilon_0}=9\times10^9\ Nm^2C^{-2}$)

JEE Main 2024 · PhysicsNumerical answerNumerical valueMediumMulti-step

JEE Main 31 January 2024, Shift 2, Physics Q55

Question 55 of 90 in this shift, Physics question 25 of 30, Section B.

The distance between charges

+q

and

-q

2l

and between

+2q

and

-2q

4l

. The electrostatic potential at point

P

at a distance

r

from center

O

-\alpha\left[\frac{ql}{r^2}\right]\times10^9\,V

, where the value of

\alpha

is __________. (Use

\frac{1}{4\pi\varepsilon_0}=9\times10^9\ Nm^2C^{-2}

)

The figure, in words

Charges on a horizontal line in order +2q, -q, O (centre), +q, -2q (from left to right); +q and -q at distance l from O, +2q and -2q at distance 2l. Point P at distance r from O on a line making 60 degrees with the horizontal axis (to the right of O).

Official answer

NTA final key.

Chapter: Electrostatic Potential and Capacitance
Topic: Electric Potential
Idea tested: Electric Potential of a Dipole

Same topic in other shifts

All Electric Potential questions

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.