List of top Physics Questions on Electrostatics

Find dipole moment of a system consisting of charge \(q_1 = 3\,\mu C\) and \(q_2 = -9\,\mu C\) with position coordinates \(\vec r_1 = 2\hat i + 3\hat j + 3\hat k\) and \(\vec r_2 = \hat i + \hat j + \hat k\) respectively.
त्रिज्या \(R\) और कुल आवेश \(+Q\) वाले एक स्थिर एकसमान आवेशित वृत्ताकार गोले पर विचार कीजिए। द्रव्यमान \(m\) वाले एक आवेशित कण \(-q\) \((q\lt \lt Q)\) को आवेशित गोले के केंद्र से \(3R\) की दूरी पर विराम अवस्था में मुक्त किया जाता है। जब यह आवेशित कण केंद्र पर पहुँचता है, तो इसकी चाल है :
(\(\epsilon_0\) निर्वात की विद्युतशीलता है, गुरुत्वाकर्षण बलों की उपेक्षा करें)
An electron falls through a distance 1.5 cm in a uniform electric field of magnitude 2.0 \(\times\) 10\(^4\) N/C from rest. The time taken to cover this distance in second is \textunderscore\textunderscore\textunderscore\textunderscore\textunderscore.
(e = 1.6 \(\times\) 10\(^{-19}\) C, m\(_e\) = 9.11 \(\times\) 10\(^{-31}\) kg)
Two electric charges \(+3.2\times10^{-19}\,\text{C}\) and \(-3.2\times10^{-19}\,\text{C}\) are placed \(2.4\,\text{\AA}\) apart to form an electric dipole. It is placed in a uniform electric field of intensity \(4\times10^5\,\text{V m}^{-1}\). The work done to rotate the electric dipole from equilibrium position by \(180^\circ\) is:
A parallel plate capacitor with circular plates of radius $R$ is being charged as shown in the figure. Let $B(r)$ be the induced magnetic field at a distance $r$ from the central axis between the plates. Assuming $d \ll R$, the ratio $\frac{B(2d)}{B(d)}$, while charging, is
A laser beam of wavelength $1\text{ }\mu\text{m}$ is split and sent into two vacuum cavities of equal length $L$ as shown in the figure. A detector can register an interference signal only if the phase difference between the returning beams is at least $5 \times 10^{-11}\text{ rad}$. A certain physical effect changes the length of cavity 2 by an amount $\Delta L$ such that $\Delta L / L \approx 10^{-21}$. The minimum cavity length (in km) needed for measuring this physical effect is approximately
All the capacitors in a given circuit are initially fully charged with all switches open. At a later time $t$, all the switches are simultaneously closed. The current flowing through the circuit at that instant is given by
An infinitely long straight wire with uniform line charge density $\lambda$ lies at a perpendicular distance $d$ from a point O. The total electric flux through the surface of a sphere of radius $R \gt d$ centred at O, is
An electromagnetic wave travels from vacuum into a non-magnetic dielectric medium with permittivity $\epsilon = 4\epsilon_0$. If the ratio ($E_0 / B_0$) of the electric field amplitude $E_0$ to the magnetic field amplitude $B_0$ in vacuum is equal to the speed of light $c$, then the corresponding ratio in the given medium is
Among the following, the waves responsible for energy transfer in vacuum are
Three positive and two negative charges each of magnitude \(q\) are placed at five of the six vertices of a regular hexagon of side \(R\). The work done to bring a negative charge \(-q\) from infinity to the centre of the hexagon is:
Two similar rods of length \( l=1 \text{ m} \) carrying equal charges \( (q) = 10^{-8} \text{ C} \) are placed as shown in figure. The electric field at point 'O' approximately is, if \( d=0.25 \text{ m} \):
A particle of charge 'q' and mass 'm' starts moving from the origin under the action of electric field, \( \vec{E}=E_{0}\hat{i} \) with a velocity \( v=v_{0}\hat{j} \). The time taken to increase its velocity to \( \frac{\sqrt{5}}{2} v_0 \) is:
\( 1\,\mu\text{C} \), \( -1\,\mu\text{C} \) charges are placed at a distance of 5 cm in forming a dipole. The amount of torque required to place this dipole perpendicular to an electric field of \( 3\times10^{5}~\text{NC}^{-1} \) is given by:
Which of the following statements are correct?
A. Inside a conductor, the electrostatic field is zero.
B. Electric field at the surface of a charged conductor does not depend on its surface charge density.
C. The interior of a charged conductor can have no excess charge in the static situation.
D. At the surface of a charged conductor, the electrostatic field must be normal to the surface at every point.
E. The electrostatic potential is zero everywhere inside a charged conductor.
Choose the correct answer from the options given below:
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R
Assertion A: In electrostatics, a conductor does not store any net charge inside.
Reason R: Inside the capacitor (with no dielectric medium), the free charge carriers, if placed between the plates of capacitor, experience force and drift.
Choose the correct answer from the options given below
Two point charges of \(1\,\text{nC}\) and \(2\,\text{nC}\) are placed at two corners of an equilateral triangle of side \(3\) cm. The work done in bringing a charge of \(3\,\text{nC}\) from infinity to the third corner of the triangle is ________ \(\mu\text{J}\). \[ \left(\frac{1}{4\pi\varepsilon_0}=9\times10^9\,\text{N m}^2\text{C}^{-2}\right) \]
Two charged conducting spheres \(S_1\) and \(S_2\) of radii \(8\) cm and \(18\) cm are connected to each other by a wire. After equilibrium is established, the ratio of electric fields on \(S_1\) and \(S_2\) spheres are \(E_{S_1}\) and \(E_{S_2}\) respectively. The value of \( \dfrac{E_{S_1}}{E_{S_2}} \) is:
Consider an electric dipole comprising two charges \(+q\) and \(-q\), each with mass \(m\), separated by a fixed distance \(d\) and initially at rest with its dipole moment pointing along \(\hat{i}\). A uniform electric field \(E\hat{j}\) is turned on at time \(t=0\) and it is turned off at \(t=t_f\), when the dipole moment makes an angle \(\theta_f\) with \(\hat{i}\). Neglecting any sources of energy loss, correct option(s) is/are:
Two charges $Q_1 = q$ and $Q_2 = mq$ are placed at the points $P_1(a, b)$ and $P_2(ma, mb)$, respectively, in the $XY$ plane, where $a, b \neq 0$ and $m \neq 0, 1$. If $V_1$ is the potential at a point in the $XY$ plane due to charge $Q_1$ and $V_2$ is the potential at that point due to charge $Q_2$. Correct statement(s) for the points at which $|V_1| = |V_2|$ is/are:
Two identical balls each of mass $\frac{40}{3}$ g carry equal and opposite charge. They are suspended from a horizontal plate by silk threads each of length 1 m with a separation of 1.5 m between points of suspension. At equilibrium, if the distance between the balls is 30 cm then magnitude of charge on each ball is (Acceleration due to gravity $= 10 \text{ ms}^{-2}$)
The electrostatic force between two charges $q_1$ and $q_2$ separated by a distance $r$ in vacuum is $F$. If a dielectric medium of dielectric constant $K$ is introduced between them, the new force is
Two charges \(+2\,\mu\text{C}\) and \(-2\,\mu\text{C}\) are placed \(2\,\text{m}\) apart. Electric field at midpoint is:
Work done in moving a charge on an equipotential surface is:
Two charges \( 2\mu\text{C} \) and \( 8\mu\text{C} \) are placed \( 2\text{ m} \) apart. Force between them is: