JEE Main Physics — Electromagnetism previous year questions with solutions.
A long solenoid carrying a current produces a magnetic field $B$ along its axis. If the current is doubled and the number of turns per $\mathrm{cm}$ is halved, the new value of magnetic field will be equal to
Two cells of the same EMF $E$ but different internal resistances ${r}_{1}$ and ${r}_{2}$ are connected in series with an external resistance $R$ as shown in the figure. The terminal potential difference across, the second cell is found to be zero. The external resistance $R$ must then be: 
An electric bulb is rated as $200W$. What will be the peak magnetic field at $4m$ distance produced by the radiations coming from this bulb? Consider this bulb as a point source with $3.5%$ efficiency.
A resistance of $40\Omega$ is connected to a source of alternating current rated $220V,50\mathrm{Hz}$. Find the time taken by the current to change from its maximum value to the rms value :
A wire $X$ of length $50\mathrm{cm}$ carrying a current of $2A$ is placed parallel to a long wire $Y$ of length $5m$. The wire $Y$ carries a current of $3A$. The distance between two wires is $5\mathrm{cm}$ and currents flow in the same direction. The force acting on the wire $Y$ is : 
The equivalent capacitance between points $A$ and $B$ in below shown figure will be _____ $\mu F$. 
A sinusoidal voltage $V(t)=210\mathrm{sin}3000t$ volt is applied to a series LCR circuit in which $L=10\mathrm{mH},C=25\mu F$ and $R=100\Omega$. The phase difference $(\Phi )$ between the applied voltage and resultant current will be
Two identical charged particles each having a mass $10g$ and charge $2.0\times {10}^{-7}C$ are placed on a horizontal table with a separation of $L$ between them such that they stay in limited equilibrium. If the coefficient of friction between each particle and the table is $0.25$, find the value of $L$. [Use $g=10{\mathrm{ms}}^{-2}$ ]
A triangular shaped wire carrying $10A$ current is placed in a uniform magnetic field of $0.5T$, as shown in figure. The magnetic force on segment $CD$ is (Given $BC=CD=BD=5\mathrm{cm}$). 
Identify the correct statements from the following descriptions of various properties of electromagnetic waves. A. In a plane electromagnetic wave electric field and magnetic field must be perpendicular to each other and direction of propagation of wave should be along electric field or magnetic field. B. The energy in electromagnetic wave is divided equally between electric and magnetic fields. C. Both electric field and magnetic field are parallel to each other and perpendicular to the direction of propagation of wave. D. The electric field, magnetic field and direction of propagation of wave must be perpendicular to each other. E. The ratio of amplitude of magnetic field to the amplitude of electric field is equal to speed of light. Choose the most appropriate answer from the options given below:
Resistance are connected in a meter bridge circuit as shown in the figure. The balancing length ${l}_{1}$ is $40\mathrm{cm}$. Now an unknown resistance $x$ is connected in series with $P$ and new balancing length is found to be $80\mathrm{cm}$ measured from the same end. Then the value of $x$ will be _____ $\Omega$. 
Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : In an uniform magnetic field, speed and energy remains the same for a moving charged particle. Reason (R): Moving charged particle experiences magnetic force perpendicular to its direction of motion.
For the given circuit the current through battery of $6V$ just after closing the switch '$S$' will be _____ $A$. 
A circular coil of 1000 turns each with area $1{m}^{2}$ is rotated about its vertical diameter at the rate of one revolution per second in a uniform horizontal magnetic field of $0.07T$. The maximum voltage generation will be _____ $V$.
A long cylindrical volume contains a uniformly distributed charge of density $\rho$. The radius of cylindrical volume is $R$. A charge particle $(q)$ revolves around the cylinder in a circular path. The kinetic energy of the particle is :
In the given figure of meter bridge experiment, the balancing length $AC$ corresponding to null deflection of the galvanometer is $40\mathrm{cm}$. The balancing length, if the radius of the wire $AB$ is doubled, will be _____ $\mathrm{cm}$. 
A $1m$ long copper wire carries a current of $1A$. If the cross section of the wire is $2.0{\mathrm{mm}}^{2}$ and the resistivity of copper is $1.7\times {10}^{-8}\Omega m$. The force experienced by moving electron in the wire is _____$\times {10}^{-23}N$ (Charge of electron$=1.6\times {10}^{-19}C$ )
A coil is placed in a time varying magnetic field. If the number of turns in the coil were to be halved and the radius of wire doubled, the electrical power dissipated due to the current induced in the coil would be (Assume the coil to be short circuited.)
Given below are two statements : Statement-I: The reactance of an ac circuit is zero. It is possible that the circuit contains a capacitor and an inductor. Statement-II: In ac circuit, the average power delivered by the source never becomes zero. In the light of the above statements, choose the correct answer from the options given below
The magnetic moment of an electron $(e)$ revolving in an orbit around nucleus with an orbital angular momentum is given by
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A: Alloys such as constantan and manganin are used in making standard resistance coils. Reason R: Constantan and manganin have very small value of temperature coefficient of resistance. In the light of the above statements, choose the correct answer from the options given below.
A $1m$ long wire is broken into two unequal parts $X$ and $Y$. The $X$ part of the wire is stretched into another wire $W$. Length of $W$ is twice the length of $X$ and the resistance of $W$ is twice that of $Y$. Find the ratio of length of $X$ and$Y$.
A teacher in his physics laboratory allotted an experiment to determine the resistance $(G)$ a galvanometer. Students took the observations for $\frac{1}{3}$ deflection in the galvanometer. Which of the below is true for measuring value of $G$?
The current sensitivity of a galvanometer can be increased by : (A) decreasing the number of turns (B) increasing the magnetic field (C) decreasing the area of the coil (D) decreasing the torsional constant of the spring Choose the most appropriate answer from the options given below :