JEE Main Physics — Electromagnetism previous year questions with solutions.
A square loop of area $25{\mathrm{cm}}^{2}$ has a resistance of $10\Omega$. The loop is placed in uniform magnetic field of magnitude $40.0T$. The plane of loop is perpendicular to the magnetic field. The work done in pulling the loop out of the magnetic field slowly and uniformly in $1.0$ sec, will be
For a moving coil galvanometer, the deflection in the coil is $0.05\mathrm{rad}$ when a current of $10\mathrm{mA}$ is passed through it. If the torsional constant of suspension wire is $4.0\times {10}^{–5}Nm{\mathrm{rad}}^{-1}$, the magnetic field is $0.01T$ and the number of turns in the coil is $200$, the area of each turn (in ${\mathrm{cm}}^{2}$ ) is :
A long solenoid is formed by winding $70$ turns ${\mathrm{cm}}^{-1}$ . If $2.0A$ current flows, then the magnetic field produced inside the solenoid is ______________. $({\mu }_{0}=4\pi \times {10}^{–7}Tm{A}^{–1})$
A circular loop of radius $R$ is carrying current $iA$. The ratio of magnetic field at the centre of circular loop and at a distance $R$ from the center of the loop on its axis is :
A conducting circular loop is placed in a uniform magnetic field of $0.4T$ with its plane perpendicular to the field. Somehow, the radius of the loop starts expanding at a constant rate of $1\mathrm{mm}{s}^{-1}$. The magnitude of induced emf in the loop at an instant when the radius of the loop is $2\mathrm{cm}$ will be _______ $\mu V$.
A square shaped coil of area $70{\mathrm{cm}}^{2}$ having $600$ turns rotates in a magnetic field of $0.4\mathrm{Wb}{m}^{–2}$, about an axis which is parallel to one of the side of the coil and perpendicular to the direction of field. If the coil completes $500$ revolution in a minute, the instantaneous emf when the plane of the coil is inclined at $60^{\circ}$ with the field, will be ______ $V$. (Take $\pi =\frac{22}{7}$)
A capacitor of capacitance $150.0\mu F$ is connected to an alternating source of emf given by $E=36\mathrm{sin}(120\pi t)V$. The maximum value of current in the circuit is approximately equal to:
The equivalent resistance between $A\text{and}B$ is _______. .
A series LCR circuit is connected to an ac source of $220V,50\mathrm{Hz}$. The circuit contain a resistance $R=100\Omega$ and an inductor of inductive reactance ${X}_{L}=79.6\Omega$. The capacitance of the capacitor needed to maximize the average rate at which energy is supplied will be ______ $\mu F$.
An alternating voltage source $V=260\mathrm{sin}(628t)$ is connected across a pure inductor of $5\mathrm{mH}$. Inductive reactance in the circuit is:
In a series $LR$ circuit with ${X}_{L}=R$, power factor is ${P}_{1}$. If a capacitor of capacitance $C$ with ${X}_{C}={X}_{L}$ is added to the circuit the power factor becomes ${P}_{2}$. The ratio of ${P}_{1}$ to ${P}_{2}$ will be :
For the given figures, choose the correct options: 
An electron is allowed to move with constant velocity along the axis of current carrying straight solenoid. (A) The electron will experience magnetic force along the axis of the solenoid. (B) The electron will not experience magnetic force. (C) The electron will continue to move along the axis of the solenoid. (D) The electron will be accelerated along the axis of the solenoid. (E) The electron will follow parabolic path-inside the solenoid. Choose the correct answer from the option given below:
Match List-I with List II of Electromagnetic waves with corresponding wavelength range: <table class="pyq-table"><tbody><tr><td></td><td>List I</td><td></td><td>List II</td></tr><tr><td>(A)</td><td>Microwave</td><td>(I)</td><td>$400\mathrm{nm}$ to $1\mathrm{nm}$</td></tr><tr><td>(B)</td><td>Ultraviolet</td><td>(II)</td><td>$1\mathrm{nm}$ to ${10}^{–3}\mathrm{nm}$</td></tr><tr><td>(C)</td><td>$X$-Ray</td><td>(III)</td><td>$1\mathrm{mm}$ to $700\mathrm{nm}$</td></tr><tr><td>(D)</td><td>Infra-red</td><td>(IV)</td><td>$0.1m$ to $1\mathrm{mm}$</td></tr></tbody></table>Choose the correct answer from the options given below:
The energy density associated with electric field $\vec{E}$ and magnetic field $\vec{B}$ of an electromagnetic wave in free space is given by (${\epsilon }_{0}-$ permittivity of free space, ${\mu }_{0}-$ permeability of free space)
The electric field and magnetic field components of an electromagnetic wave going through vacuum is described by ${E}_{x}={E}_{0}\mathrm{sin}(kz-\omega t)$ ${B}_{y}={B}_{0}\mathrm{sin}(kz-\omega t)$ Then the correct relation between ${E}_{0}$ and ${B}_{0}$ is given by
Match the List-I with List-II: <table class="pyq-table"><tbody><tr><td></td><td>List I</td><td></td><td>List II</td></tr><tr><td>A</td><td>Microwaves</td><td>I</td><td>Radioactive decay of the nucleus</td></tr><tr><td>B</td><td>Gamma rays</td><td>II</td><td>Rapid acceleration and deceleration of electron in aerials</td></tr><tr><td>C</td><td>Radio waves</td><td>III</td><td>Inner shell electrons</td></tr><tr><td>D</td><td>X-rays</td><td>IV</td><td>Klystron valve</td></tr></tbody></table>Choose the correct answer from the options given below:
A uniform metallic wire carries a current $2A$, when $3.4V$ battery is connected across it. The mass of uniform metallic wire is $8.92\times {10}^{-3}\mathrm{kg}$, density is $8.92\times {10}^{3}\mathrm{kg}{m}^{-3}$ and resistivity is $1.7\times {10}^{-8}\Omega -m$ The length of wire is :
A $600\mathrm{pF}$ capacitor is charged by $200V$ supply. It is then disconnected from the supply and is connected to another uncharged $600\mathrm{pF}$ capacitor. Electrostatic energy lost in the process is _____ $\mu J$.
 As per the given graph, choose the correct representation for curve $A$ and curve $B$ {Where ${X}_{C}=$ Reactance of pure capacitive circuit connected with A.C. source ${X}_{L}=$ Reactance of pure inductive circuit connected with A.C. source $R=$ Impedance of pure resistive circuit connected with A.C. source $Z=$ Impedance of the $LCR$ series circuit }
The ratio of average electric energy density and total average energy density of electromagnetic wave is:
The source of time varying magnetic field may be (A) a permanent magnet (B) an electric field changing linearly with time (C) direct current (D) a decelerating charge particle (E) an antenna fed with a digital signal Choose the correct answer from the options given below.
A wire of length $1m$ moving with velocity $8m{s}^{-1}$ at right angles to a magnetic field of $2T$. The magnitude of induced emf, between the ends of wire will be ___________.
A series LCR circuit consists of $R=80Ω$. ${X}_{L}=100Ω$, and ${X}_{C}=40Ω$. The input voltage is $2500\mathrm{cos}(100\pi t)V$. The amplitude of current, in the circuit, is _____ $A$.