JEE Main Physics — Electromagnetism previous year questions with solutions.
The ratio of the equivalent resistance of the network (shown in figure) between the points $a$ and $b$ when switch is open and switch is closed is $x:8$. The value of $x$ is 
The electric field in an electromagnetic wave is given by $E=(50N{C}^{-1})\mathrm{sin}\omega (t-\frac{x}{c})$ The energy contained in a cylinder of volume $V$ is $5.5\times {10}^{-12}J.$ The value of $V$ is _______ ${\mathrm{cm}}^{3}.$ (given ${\epsilon }_{0}=8.8\times {10}^{-12}{C}^{2}{N}^{-1}{m}^{-2}$)
There are two infinitely long straight current-carrying conductors and they are held at right angles to each other so that their common ends meet at the origin as shown in the figure given below. The ratio of current in both conductors is $1:1$. The magnetic field at point $P$ is$_________.$ 
Calculate the amount of charge on capacitor of $4\mu F.$ The internal resistance of battery is $1\Omega :$ 
The alternating current is given by, $i={\sqrt{42}\mathrm{sin}(\frac{2\pi }{T}t)+10}A$. The R.M.S. value of this current is __________ $A$.
In a circuit consisting of a capacitance and a generator with alternating emf, ${E}_{g}={E}_{go}sin\omega t,{V}_{C}$ and ${I}_{C}$ are the voltage and current. Correct phasor diagram for such circuit is 
A radiation is emitted by $1000W$ bulb and it generates an electric field and magnetic field at $P$, placed at a distance of $2m$. The efficiency of the bulb is $1.25%$. The value of peak electric field at $P$ is $x\times {10}^{-1}V{m}^{-1}$. Value of $x$ is (Rounded-off to the nearest integer) [Take ${\epsilon }_{0}=8.85\times {10}^{-12}{C}^{2}{N}^{-1}{m}^{-2},c=3\times {10}^{6}m{s}^{-1}$]
A square loop of side $20\mathrm{cm}$ and resistance $1\Omega$ is moved towards right with a constant speed ${v}_{0}.$ The right arm of the loop is in a uniform magnetic field of $5T.$ The field is perpendicular to the plane of the loop and is going into it. The loop is connected to a network of resistors each of value $4\Omega .$ What should be the value of ${v}_{0}$ so that a steady current of $2\mathrm{mA}$ flows in the loop ? 
In an electrical circuit, a battery is connected to pass $20C$ of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at $15V$. The workdone by the battery is _______ $J$
Match 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>$\omega L>\frac{1}{\omega C}$</td><td>(i)</td><td>Current is in phase with emf</td></tr><tr><td>(b)</td><td>$\omega L=\frac{1}{\omega C}$</td><td>(ii)</td><td>Current lags behind the applied emf</td></tr><tr><td>(c)</td><td>$\omega L<\frac{1}{\omega C}$</td><td>(iii)</td><td>Maximum current occurs</td></tr><tr><td>(d)</td><td>Resonant frequency</td><td>(iv)</td><td>Current leads the emf</td></tr></tbody></table>Choose the correct answer from the options given below.
Statement I : The ferromagnetic property depends on temperature. At high temperature, ferromagnet becomes paramagnet. Statement II : At high temperature, the domain wall area of a ferromagnetic substance increases. In the light of the above statements, choose the most appropriate answer from the options given below:
The temperature of $3.00\mathrm{mol}$ of an ideal diatomic gas is increased by $40.0^{\circ}C$ without changing the pressure of the gas. The molecules in the gas rotate but do not oscillate. If the ratio of change in internal energy of the gas to the amount of workdone by the gas is $\frac{x}{10}.$ Then the value of $x$ (round off to the nearest integer) is $_________.$ $($ Given$R=8.31J{\mathrm{mol}}^{-1}{K}^{-1})$
A charge $Q$ is moving $d\vec{l}$ distance in the magnetic field $\vec{B}$. Find the value of work done by $\vec{B}$.
In an LCR series circuit, the power factor is unity. What is the phase difference between current and voltage?
In the given figure the magnetic flux through the loop increases according to the relation ${\phi }_{B}(t)=10{t}^{2}+20t$, where ${\phi }_{B}$ is in milliwebers and $t$ is in seconds. The magnitude of current through $R=2\Omega$ resistor at $t=5s$ is _____ $\mathrm{mA}.$ 
The magnetic field in a region is given by $\vec{B}={B}_{0}(\frac{x}{a})\hat{k}$. A square loop of side d is placed with its edges along the $x$ and $y$ axes. The loop is moved with a constant velocity $\vec{v}={v}_{0}\hat{i}$. The emf induced in the loop is : 
A circular conducting coil of radius $1m$ is being heated by the change of magnetic field $\vec{B}$ passing perpendicular to the plane in which the coil is laid. The resistance of the coil is $2\mu \Omega$. The magnetic field is slowly switched off such that its magnitude changes in time as $B=\frac{4}{\pi }\times {10}^{-3}T(1-\frac{t}{100})$ The energy dissipated by the coil before the magnetic field is switched off completely is $E=______\mathrm{mJ}$.
An $AC$ source rated $220V,50\mathrm{Hz}$ is connected to a resistor. The time taken by the current to change from its maximum to the rms value is :
An AC circuit has an inductor and a resistor of resistance $R$ in series, such that ${X}_{L}=3R$. Now, a capacitor is added in series such that ${X}_{C}=2R$. the ratio of the new power factor with the old power factor of the circuit is $\sqrt{5}:x$. The value of $x$ is
Two circuits are shown in figure $(a)$ and $(b)$. At a frequency of _______ $\mathrm{rad}{s}^{-1}$ the average power dissipated in one cycle will be the same in both the circuits. 
In a series LCR circuit, the inductive reactance $({X}_{L})$ is $10\Omega$ and the capacitive reactance $({X}_{C})$ is $4\Omega$. The resistance $(R)$ in the circuit is $6\Omega$. The power factor of the circuit is :
The time taken for the magnetic energy to reach $25%$ of its maximum value, when a solenoid of resistance $R$, inductance $L$ is connected to a battery, is :
The electric field in a plane electromagnetic wave is given by $\vec{E}=200\mathrm{cos}[(0.5\times {10}^{3}{m}^{-1})x-(1.5\times {10}^{11}\mathrm{rad}{s}^{-1})t]V{m}^{-1}\hat{j}$. If this wave falls normally on a perfectly reflecting surface having an area of $100{\mathrm{cm}}^{2}$. If the radiation pressure exerted by the E.M. wave on the surface during a $10\mathrm{min}$ exposure is $\frac{k}{{10}^{9}}N{m}^{-2}$. Find the value of $k$
A linearly polarised electromagnetic wave in vacuum is $E=3.1\mathrm{cos}[(1.8)z-(5.4\times {10}^{6})t]\hat{i}N{C}^{-1}$ is incident normally on a perfectly reflecting wall at $z=a$. Choose the correct option.