List of top Physics Questions on Electromagnetism

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A): Choke coil is simply a coil having a large inductance but a small resistance. Choke coils are used with fluorescent mercury-tube fittings. If household electric power is directly connected to a mercury tube, the tube will be damaged.
Reason (R): By using the choke coil, the voltage across the tube is reduced by a factor $\frac{R}{\sqrt{R^2 + \omega^2 L^2}}$, where $\omega$ is the frequency of the supply across resistor $R$ and inductor $L$. If the choke coil were not used, the voltage across the resistor would be the same as the applied voltage.
In light of the above statements, choose the most appropriate answer from the options given below:

A charge particle moving in magnetic field $B$, has components of velocity along $B$ as well as perpendicular to $B$. The path of the charge particle will be:

A charge particle moving in magnetic field $B$, has components of velocity along $B$ as well as perpendicular to $B$. The path of the charge particle will be:

A heavy box of mass 50 kg is moving on a horizontal surface. If the coefficient of kinetic friction between the box and the horizontal surface is 0.3, then the force of kinetic friction is:

In the circuit shown, find $C$ if the effective capacitance of the whole circuit is to be 0.5 $\mu F$. All values in the circuit are in $\mu F$. 

A circular coil having 200 turns, $2.5 \times 10^{-4} \text{ m}^2$ area and carrying 100 $\mu$A current is placed in a uniform magnetic field of 1 T. Initially the magnetic dipole moment ($\vec{M}$) was directed along $\vec{B}$. Amount of work, required to rotate the coil through $90^\circ$ from its initial orientation such that $\vec{M}$ becomes perpendicular to $\vec{B}$, is ________ $\mu$J.

The current in an inductor is given by I = (3t + 8) where t is in second. The magnitude of induced emf produced in the inductor is 12 mV. The self inductance of the inductor _______ mH.

A galvanometer of resistance $100 \, \Omega$ when connected in series with $400 \, \Omega$ measures a voltage of up to $10 \, V$. The value of resistance required to convert the galvanometer into an ammeter to read up to $10 \, A$ is $x \times 10^{-2} \, \Omega$. The value of $x$ is:

A solenoid of length 0.5 m has a radius of 1 cm and is made up of 'm' number of turns. It carries a current of 5 A. If the magnitude of the magnetic field inside the solenoid is $6.28 \times 10^{-3}$ T, then the value of m is:

A square loop PQRS having 10 turns, area $3.6 \times 10^{-3} \, \text{m}^2$, and resistance $100 \, \Omega$ is slowly and uniformly being pulled out of a uniform magnetic field of magnitude $B = 0.5 \, \text{T}$ as shown. Work done in pulling the loop out of the field in $1.0 \, \text{s}$ is ______ $\times 10^{-6} \, \text{J}$.

An electron with kinetic energy $5 \, \text{eV}$ enters a region of uniform magnetic field of $3 \, \mu\text{T}$ perpendicular to its direction. An electric field $E$ is applied perpendicular to the direction of velocity and magnetic field. The value of $E$, so that the electron moves along the same path, is ______ $\text{NC}^{-1}$.
Given: mass of electron = $9 \times 10^{-31} \, \text{kg}$, electric charge = $1.6 \times 10^{-19} \, \text{C}$

Given below are two statements:
Statement (I): When currents vary with time, Newton’s third law is valid only if momentum carried by the electromagnetic field is taken into account. 
Statement (II): Ampere’s circuital law does not depend on Biot-Savart’s law. 
In the light of the above statements, choose the correct answer from the options given below:

A charged particle moving with a velocity $\vec{v} = v_1\hat{i} + v_2\hat{j} + v_3\hat{k}$ in a magnetic field $\vec{B}$ experiences a force $\vec{F} = F_1\hat{i} + F_2\hat{j}$. Here $v_1, v_2, F_1, F_2$ are all constants. Then $\vec{B}$ can be:

The given circuit shows a uniform straight wire AB of 40 cm length fixed at both ends. In order to get zero reading in the galvanometer G, the free end of J is to be placed from B at:

Match List I with List II

List I	List II
A. $\oint \vec{B} \cdot d\vec{l} = \mu_0 i_c + \mu_0 \epsilon_0 \frac{d\phi_E}{dt}$	I. Gauss' law for electricity
B. $\oint \vec{E} \cdot d\vec{l} = -\frac{d\phi_B}{dt}$	II. Gauss' law for magnetism
C. $\oint \vec{E} \cdot d\vec{A} = \frac{Q}{\epsilon_0}$	III. Faraday law
D. $\oint \vec{B} \cdot d\vec{A} = 0$	IV. Ampere – Maxwell law

Choose the correct answer from the options given below

The magnetic flux density created by an infinitely long conductor carrying a current $I$ at a radial distance $R$ is:

A solenoid has length $l$, number of turns $N$, and area of cross-section $A$. Its self-inductance $L$ is:

The frequency of the charged particle circular at right angles to a uniform magnetic field does not depend upon the