JEE Main Physics — Electromagnetism previous year questions with solutions.
A parallel plate capacitor filled with a medium of dielectric constant $10$, is connected across a battery and is charged. The dielectric slab is replaced by another slab of dielectric constant $15$. Then the energy of capacitor will
If the charge on a capacitor is increased by $2C$, the energy stored in it increases by $44%$. The original charge on the capacitor is (in $C$)
A direct current of $4A$ and an alternating current of peak value $4A$ flow through resistance of $3\Omega$ and $2\Omega$ respectively. The ratio of heat produced in the two resistances in same interval of time will be :
The electric field in an electromagnetic wave is given by $E=56.5\mathrm{sin}\omega (\frac{t-x}{c}){\mathrm{NC}}^{-1}$. Find the intensity of the wave if it is propagating along $x$-axis in the free space. (Given ${\epsilon }_{0}=8.85\times {10}^{-12}{C}^{2}{N}^{-1}{m}^{-2}$)
Which is the correct ascending order of wavelengths?
As shown in the figure an inductor of inductance $200\mathrm{mH}$ is connected to an $\mathrm{AC}$ source of emf $220V$and frequency $50\mathrm{Hz}$. The instantaneous voltage of the source is $0V$ when the peak value of current is $\frac{\sqrt{a}}{\pi }A$. The value of $a$ is _____ . 
Light wave travelling in air along $x$-direction is given by ${E}_{y}=540\mathrm{sin}\pi \times {10}^{4}(x-ct)V{m}^{-1}$. Then, the peak value of magnetic field of wave will be (Given $c=3\times {10}^{8}m{s}^{-1}$)
The magnetic field at a distance r from a long straight wire carrying current I is:
A closely wounded circular coil of radius $5\mathrm{cm}$ produces a magnetic field of $37.68\times {10}^{-4}T$ at its center. The current through the coil is _____ $A$. [Given, number of turns in the coil is $100$ and $\pi =3.14$]
A charge particle is moving in a uniform magnetic field $(2\hat{i}+3\hat{j})T$. If it has an acceleration of $(\alpha \hat{i}-4\hat{j})m{s}^{-2}$, then the value of $\alpha$ will be
${B}_{X}$ and ${B}_{Y}$ are the magnetic field at the centre of two coils of two coils $X$ and $Y$ respectively, each carrying equal current. If coil $X$ has $200$ turns and $20\mathrm{cm}$ radius and coil $Y$ has $400$ turns and $20\mathrm{cm}$ radius, the ratio of ${B}_{X}$ and ${B}_{Y}$ is
Given below are two statements : Statement $I$: The electric force changes the speed of the charged particle and hence changes its kinetic energy; whereas the magnetic force does not change the kinetic energy of the charged particle. Statement $\mathrm{II}$: The electric force accelerates the positively charged particle perpendicular to the direction of electric field. The magnetic force accelerates the moving charged particle along the direction of magnetic field. In the light of the above statements, choose the most appropriate answer from the options given below :
In the given figure, the value of ${V}_{0}$ will be _____ $V$. 
A $10\Omega ,20\mathrm{mH}$ coil carrying constant current is connected to a battery of $20V$ through a switch. Now after switch is opened current becomes zero in $100\mu s$. The average e.m.f. induced in the coil is _____ $V$.
A conducting circular loop is placed in $X-Y$ plane in presence of magnetic field $\vec{B}=(3{t}^{3}\hat{j}+3{t}^{2}\hat{k})$ in SI unit. If the radius of the loop is $1m$, the induced emf in the loop, at time, $t=2s$ is $n\pi V$. The value of $n$ is _____ .
In a coil of resistance $8\Omega$, the magnetic flux due to an external magnetic field varies with time as $\phi =\frac{2}{3}(9-{t}^{2})$. The value of total heat produced in the coil, till the flux becomes zero, will be _____ $J$.
Sun light falls normally on a surface of area $36{\mathrm{cm}}^{2}$ and exerts an average force of $7.2\times {10}^{-9}N$ within a time period of $20$ minutes. Considering a case of complete absorption, the energy flux of incident light is
An alternating emf $E=440\mathrm{sin}100\pi t$ is applied to a circuit containing an inductance of $\frac{\sqrt{2}}{\pi }H$. If an a.c. ammeter is connected in the circuit, its reading will be :
A circuit element $X$ when connected to an AC supply of peak voltage $100V$ gives a peak current of $5A$ which is in phase with the voltage. A second element $Y$ when connected to the same AC supply also gives the same value of peak current which lags behind the voltage by $\frac{\pi }{2}$. If $X$ and $Y$ are connected in series to the same supply, what will be the rms value of the current in ampere?
A series LCR circuit has $L=0.01H,R=10\Omega$ and $C=1\mu F$ and it is connected to ac voltage of amplitude $({V}_{m})50V$. At frequency $60%$ lower than resonant frequency, the amplitude of current will be approximately
The frequencies at which the current amplitude in an LCR series circuit becomes $\frac{1}{\sqrt{2}}$ times its maximum value, are $212\mathrm{rad}{s}^{-1}$ and $232\mathrm{rad}{s}^{-1}$. The value of resistance in the circuit is $R=5\Omega$. The self inductance in the circuit is _____ $\mathrm{mH}$.
The effective current $I$ in the given circuit at very high frequencies will be _____ $A$. 
An inductor of $0.5\mathrm{mH}$, a capacitor of $200\mu F$ and a resistor of $2\Omega$ are connected in series with a $220V$ ac source. If the current is in phase with the emf, the frequency of ac source will be ______$\times {10}^{2}\mathrm{Hz}$.
To light, a $50W,100V$ lamp is connected, in series with a capacitor of capacitance $\frac{50}{\pi \sqrt{x}}\mu F$, with $200V,50\mathrm{Hz}\mathrm{AC}$ source. The value of $x$ will be _____ .