Question
Obtain an expression for the electric potential at a point due to several point charges.

Answer

Consider a point $P$ at distances $r_1, r_2, r_3, \ldots, r_N$ from point charges $q_1, q_2, q_3$,
$q _{ N }$, respectively.
The electric potentials of $P$ due to the individual charges are
$V _1=\frac{1}{4 \pi \varepsilon_0} \frac{q_1}{r_1},$
$V_2=\frac{1}{4 \pi \varepsilon_0} \frac{q_2}{r_2}$
$V _{ N }=\frac{1}{4 \pi \varepsilon_0} \frac{q_N}{r_N}$
Since potential is a scalar quantity, the potential of $P$ due to all the charges is the algebraic sum of the potentials due to the individual charges.
$\therefore V = V _1+ V _1+\ldots \ldots . . .+ V _{ N }$
$=\frac{1}{4 \pi \varepsilon_0}\left(\frac{q_1}{r_1}+\frac{q_2}{r_2}+\ldots+\frac{q_N}{r_N}\right)$
$=\frac{1}{4 \pi \varepsilon_0} \sum_{i=1}^N \frac{q_i}{r_i}$
$[$Note : Electric potential is a scalar quantity. To calculate the resultant potential due to two or more point charges, the potentials due to individual charges are added as simple scalars along with its sign, determined by the sign of the $q$ that produces $V.]$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

State the differential equation of linear simple harmonic motion. Hence obtain the expression for acceleration, velocity and displacement of a particle performing linear S.H.M.
A satellite moves around the Earth in an elliptical orbit such that at perigee (closest approach) it is two Earth radii above the Earth's surface. At apogee (farthest position), it travels with one-fourth the speed it has at perigee. In terms of the Earth's radius R, what is the maximum distance of the satellite from the Earth's surface?
A particle performs SHM of period $12$ seconds and amplitude $8 cm$. If initially the particle is at the positive extremity, how much time will it take to cover a distance of $6 cm$ from that position?
Derive an expression for the terminal velocity of the sphere falling under gravity through a viscous medium.
Explain the capillary action.

Explain : Each translational and rotational degree of freedom contributes only one quadratic term to the energy but one vibrational mode contributes two quadratic terms.
In a parallel plate capacitor with air between the plates, each plate has an area of $6 \times 10^{-3}\ m^2$​​​​​​​ and the separation between the plates is $2 mm$.
i) Calculate the capacitance of the capacitor.
ii) If this capacitor is connected to $100\ V$ supply, what would be the charge on each plate?
iii) How would charge on the plates be affected if a $2$ mm thick mica sheet of $k = 6$ is inserted between the plates while the voltage supply remains connected ?
Consider a heavy string X and a light string Y joined together at point O. Explain what happens when a wave pulse
(1) travelling from the string X reaches the junction O
(2) travelling from the string Y reaches the junction O.
What is interference?
A galvanometer of resistance $50 \Omega$ has a current sensitivity of $5 div / mA$. The instrument has $25$ divisions. How will you convert it into a voltmeter of range $0-50 V$ ?