JEE Main Physics — Electromagnetism previous year questions with solutions.
The ratio of average electric energy density and total average energy density of electromagnetic wave is:
The number of turns of the coil of a moving coil galvanometer is increased in order to increase current sensitivity by $50%$. The percentage change in voltage sensitivity of the galvanometer will be :
The number density of free electrons in copper is nearly $8\times {10}^{28}{m}^{-3}$. A copper wire has its area of cross-section $=2\times {10}^{-6}{m}^{2}$ and is carrying a current of $3.2A$. The drift speed of the electrons is _____$\times {10}^{-6}m{s}^{-1}$.
The magnitude of magnetic induction at mid-point $O$ due to current arrangement as shown in figure will be .
The magnetic moments associated with two closely wound circular coils $A$ and $B$ of radius ${r}_{A}=10\mathrm{cm}\text{and}{r}_{B}=20\mathrm{cm}$ respectively are equal if: (Where ${N}_{A},{I}_{A}\text{and}{N}_{B},{I}_{B}$ are number of turn and current of $A\text{and}B$ respectively)
The magnetic intensity at the centre of a long current carrying solenoid is found to be $1.6\times {10}^{3}A{m}^{-1}$. If the number of turns is $8$ per $\mathrm{cm}$, then the current flowing through the solenoid is $______A.$
The magnetic field B crossing normally a square metallic plate of area $4{m}^{2}$ is changing with time as shown in figure. The magnitude of induced emf in the plate during $t=2s$ to $t=4s$, is _____ $mV$. 
The induced emf can be produced in a coil by A. moving the coil with uniform speed inside uniform magnetic field B. moving the coil with non uniform speed inside uniform magnetic field C. rotating the coil inside the uniform magnetic field D. changing the area of the coil inside the uniform magnetic field Choose the correct answer from the options given below:
The equivalent resistance of the circuit shown below between points $a$ and $b$ is : 
The equivalent resistance between $AandB$ of the network shown in figure: 
The equivalent resistance between $A\text{and}B$ is _______. .
The equivalent resistance between $A$ and $B$ as shown in figure is: 
The equivalent capacitance of the combination shown is 
The energy of an electromagnetic wave contained in a small volume oscillates with
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 potential at the centre of two concentric half rings of radii ${R}_{1}$ and ${R}_{2}$, having same linear charge density $\lambda$ is .
The electric field in an electromagnetic wave is given as $\vec{E}=20\mathrm{sin}\omega (t-\frac{x}{c})\vec{j}N{C}^{-1}$, where $\omega$ and $c$ are angular frequency and velocity of electromagnetic wave respectively. The energy contained in a volume of $5\times {10}^{-4}{m}^{3}$ will be (Given ${\epsilon }_{0}=8.85\times {10}^{-12}{C}^{2}{N}^{-1}{m}^{-2}$)
The electric field due to a short electric dipole at a large distance $(r)$ from center of dipole on the equatorial plane varies with distance as :
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
The electric current in a circular coil of four turns produces a magnetic induction $32T$ at its centre. The coil is unwound and is rewound into a circular coil of single turn, the magnetic induction at the centre of the coil by the same current will be :
The drift velocity of electrons for a conductor connected in an electrical circuit is ${V}_{d}$. The conductor is now replaced by another conductor with same material and same length but double the area of cross-section. The applied voltage remains same. The new drift velocity of electrons will be
The distance between two plates of a capacitor is $d$ and its capacitance is ${C}_{1}$, when air is the medium between the plates. If a metal sheet of thickness $\frac{2d}{3}$ and of the same area as plate is introduced between the plates, the capacitance of the capacitor becomes ${C}_{2}$ . The ratio $\frac{{C}_{2}}{{C}_{1}}$ is
The current sensitivity of moving coil galvanometer is increased by $25%$. This increase is achieved only changing in the number of turns of coils and area of cross section of the wire while keeping the resistance of galvanometer coil constant. The percentage change in the voltage sensitivity will be:
The current required to be passed through a solenoid of $15\mathrm{cm}$ length and $60$ turns in order to demagnetise a bar magnet of magnetic intensity $2.4\times {10}^{3}A{m}^{–1}$ is ________ $A$.