JEE Main Physics — Electromagnetism previous year questions with solutions.
A regular polygon of $6$ sides is formed by bending a wire of length $4\pi$ meter. If an electric current of $4\pi \sqrt{3}A$ is flowing through the sides of the polygon, the magnetic field at the centre of the polygon would be $x\times {10}^{-7}T.$ The value of $x$ is ______.
In an electrical circuit drawn below the amount of charge stored in the capacitor is _______ $\mu C.$ 
Suppose a uniformly charged wall provides a uniform electric field of $2\times {10}^{4}N{C}^{-1}$ normally. A charged particle of mass $2g$ being suspended through a silk thread of length $20\mathrm{cm}$ and remain stayed at a distance of $10\mathrm{cm}$ from the wall. Then the charge on the particle will be $\frac{1}{\sqrt{x}}\mu C$ where $x=$ ________ [use $g=10m{s}^{-2}$]
A potential divider circuit is shown in figure. The output voltage ${V}_{0}$ is 
A proton moving with a constant velocity passes through a region of space without any change in its velocity. If $\vec{E}$ and $\vec{B}$ represent the electric and magnetic fields respectively, then the region of space may have : (A) $E=0,B=0$; (B) $E=0,B\neq 0$; (C) $E\neq 0,B=0$; (D) $E\neq 0,B\neq 0$ Choose the most appropriate answer from the options given below :
A galvanometer having coil resistance $10\Omega$ shows a full scale deflection for a current of $3\mathrm{mA}$. For it to measure a current of $8A$, the value of the shunt should be:
The electric potential at the surface of an atomic nucleus $(Z=50)$ of radius $9\times {10}^{-13}\mathrm{cm}$ is $\alpha \times {10}^{6}V$. What is the value of $\alpha$? (Charge of proton $1.6\times {10}^{-19}C$)
A straight magnetic strip has a magnetic moment of $44 \mathrm{Am}^2$. If the strip is bent in a semicircular shape, its magnetic moment will be _______ $\mathrm{Am}^2$. (given $\pi=\frac{22}{7}$ )
In the given figure an ammeter A consists of a $240 \Omega$ coil connected in parallel to a $10 \Omega$ shunt. The reading of the ammeter is $\qquad$ $\mathrm{mA}$ 
A $16\Omega$ wire is bend to form a square loop. A $9V$ battery with internal resistance $1\Omega$ is connected across one of its sides. If a $4\mu F$ capacitor is connected across one of its diagonals, the energy stored by the capacitor will be $\frac{x}{2}\mu J$, where $x=$______.
A parallel plate capacitor with plate separation $5\mathrm{mm}$ is charged up by a battery. It is found that on introducing a dielectric sheet of thickness $2\mathrm{mm}$, while keeping the battery connections intact, the capacitor draws $25%$ more charge from the battery than before. The dielectric constant of the sheet is ____.
The primary side of a transformer is connected to $230V,50\mathrm{Hz}$ supply. The turn ratio of primary to secondary winding is $10:1$. Load resistance connected to the secondary side is $46\Omega$. The power consumed in it is:
Match List I with List II  Chose the correct answer from the options given below
A wire of length $10\mathrm{cm}$ and radius $\sqrt{7}\times {10}^{-4}m$ connected across the right gap of a meter bridge. When a resistance of $4.5\Omega$ is connected on the left gap by using a resistance box, the balance length is found to be at $60\mathrm{cm}$ from the left end. If the resistivity of the wire is $R\times {10}^{-7}\Omega m$, then value of $R$ is :
In a co-axial straight cable, the central conductor and the outer conductor carry equal currents in opposite directions. The magnetic field is zero :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason(R) Assertion (A) : Work done by electric field on moving a positive charge on an equipotential surface is always zero. Reason (R) : Electric lines of forces are always perpendicular to equipotential surfaces. In the light of the above statements, choose the most appropriate answer from the options given below :
A wire of resistance $20 \Omega$ is divided into 10 equal parts, resulting pairs. A combination of two parts are connected in parallel and so on. Now resulting pairs of parallel combination are connected in series. The equivalent resistance of final combination is _____ $\Omega$.
A square loop of side $15 \mathrm{~cm}$ being moved towards right at a constant speed of 2 $\mathrm{cm} / \mathrm{s}$ as shown in figure. The front edge enters the $50 \mathrm{~cm}$ wide magnetic field at $t=$ 0 . The value of induced emf in the loop at $t=10 \mathrm{~s}$ will be : 
A bulb and a capacitor are connected in series across an ac supply. A dielectric is then placed between the plates of the capacitor. The glow of the bulb:
A solenoid of length $0.5 \mathrm{~m}$ has a radius of $1 \mathrm{~cm}$ and is made up of ' $\mathrm{m}$ ' number of turns. It carries a current of $5 \mathrm{~A}$. If the magnitude of the magnetic field inside the solenoid is $6.28 \times 10^{-3} \mathrm{~T}$ then the value of $m$ is _____.
A power transmission line feeds input power at $2.3\mathrm{kV}$ to a step down transformer with its primary winding having $3000\text{turns}$. The output power is delivered at $230V$ by the transformer. The current in the primary of the transformer is $5A$ and its efficiency is $90%$. The winding of transformer is made of copper. The output current of transformer is ____$A$.
A galvanometer $(G)$ of $2\Omega$ resistance is connected in the given circuit. The ratio of charge stored in ${C}_{1}$ and ${C}_{2}$ is: 
To determine the resistance $(R)$ of a wire, a circuit is designed below. The $V-I$ characteristic curve for this circuit is plotted for the voltmeter and the ammeter readings as shown in figure. The value of $R$ is ______ $\Omega$. 
Five charges $+q,+5 q,-2 q,+3 q$ and $-4 q$ are situated as shown in the figure. The electric flux due to this configuration through the surface $S$ is : 