Electric potential due to a charge, a dipole and a system — NEET & JEE Questions

Question 1 · difficulty L1 · recall

The electric potential at distance $r$ from a point charge $q$ in vacuum is

• A. $V=\dfrac{kq}{r}$
• B. $V=\dfrac{kq}{r^2}$
• C. $V=kqr$
• D. $V=\dfrac{kr}{q}$

Question 2 · difficulty L2 · understanding

Electric potential is a

• A. scalar quantity
• B. vector quantity
• C. tensor quantity only
• D. dimensionless quantity

Question 3 · difficulty L2 · understanding

At the perpendicular bisector of an ideal electric dipole with charges $+q$ and $-q$, the net electric potential is

• A. zero
• B. positive
• C. negative
• D. infinite

Question 4 · difficulty L2 · understanding

For a system of point charges, the electric potential at a point is found by

• A. algebraically summing $kq_i/r_i$ for all charges
• B. vector-adding $kq_i/r_i$
• C. multiplying all individual potentials
• D. using only the nearest charge

Question 5 · difficulty L3 · application

What is the potential $0.20\,\text{m}$ from a $+2\,\mu\text{C}$ charge? Take $k=9\times10^9$ SI.

• A. $9\times10^3$ V
• B. $9\times10^4$ V
• C. $9\times10^5$ V
• D. $1.8\times10^5$ V

Question 6 · difficulty L3 · application

Two charges $+2\,\mu\text{C}$ and $-2\,\mu\text{C}$ are equidistant from point P. What is the net potential at P?

• A. zero
• B. always positive
• C. always negative
• D. depends on the direction of the electric field

Question 7 · difficulty L3 · application

A point is $0.30\,\text{m}$ from a $+1\,\mu\text{C}$ charge and $0.20\,\text{m}$ from a $-1\,\mu\text{C}$ charge. Take $k=9\times10^9$. What is the potential?

• A. $-1.5\times10^4$ V
• B. $+1.5\times10^4$ V
• C. $-7.5\times10^4$ V
• D. 0 V

Question 8 · difficulty L3 · application

An ideal dipole of moment $p$ is observed at a distant point on its axial line at distance $r$. The potential is proportional to

• A. $p/r^2$
• B. $p/r$
• C. $p/r^3$
• D. $pr$

Question 9 · difficulty L4 · application

Charges $+q$, $+q$ and $-q$ are at three vertices of a square of side $a$. What is the potential at the fourth vertex if the negative charge is diagonally opposite that vertex?

• A. $\dfrac{kq}{a}\left(2-\dfrac{1}{\sqrt2}\right)$
• B. $\dfrac{kq}{a}\left(\sqrt2-2\right)$
• C. $\dfrac{kq}{a\sqrt2}$
• D. 0

Question 10 · difficulty L4 · application

At a distant point, the potential due to an ideal dipole is zero when the position vector makes what angle with the dipole moment?

• A. $0^\circ$
• B. $45^\circ$
• C. $90^\circ$
• D. $180^\circ$