NEET UG Physics — Electromagnetism previous year questions with solutions.
A current loop in a magnetic field
A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced emf is
A $12 \mathrm{~cm}$ wire is given a shape of a right angled triangle $A B C$ having sides $3 \mathrm{~cm}$, $4 \mathrm{~cm}$ and $5 \mathrm{~cm}$ as shown in the figure. The resistance between two ends (AB, $B C, C A)$ of the respective sides are measured one by one by a multi-meter. The resistance will be in the ratio: 
When a proton is released from rest in a room, it starts with an initial acceleration $a_0$ towards west. When it is projected towards north with a speed $v_0$ it moves with an initial acceleration $3 a_0$ towards west. The electric and magnetic fields in the room are
A charge ' $q$ ' is placed at the centre of the line joining two equal charges ' $Q$ '. The system of three charges will be in equilibrium if ' $q$ ' is equal to:
Two metallic spheres of radii $1 \mathrm{~cm}$ and $3 \mathrm{~cm}$ are given charges of $-1 \times 10^{-2} \mathrm{C}$ and $5 \times 10^{-2} \mathrm{C}$, respectively. If these are connected by a conducting wire, the final charge on the bigger sphere is
What is the flux through a cube of side $a$ if a point charge of $q$ is a one of its corner?
In the circuit shown the cells $A$ and $B$ have negligible resistances. For $V_A=12 \mathrm{~V}$, $R_1=500 \Omega$ and $R=100 \Omega$ the galvanometer (G) shows no deflection. The value of $V_B$ is 
A ring is made of a wire having a resistance $R_0=12 \Omega$. Find the points $A$ and $B$, as shown in the figure, at which a current carrying conductor should be connected so that the resistance $R$ of the sub circuit between these points is equal to $8 / 3 \Omega$ 
A coil of resistance $400 \Omega$ is placed in a magnetic field. If the magnetic flux $\phi(\mathrm{Wb})$ linked with the coil varies with time $t$ (sec) as $\phi=50 t^2+4$ The current in the coil at $t=2 \mathrm{~s}$ is
The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to
The instantaneous values of alternating current and voltages in a circuit are given as $$ \begin{aligned} & i=\frac{1}{\sqrt{2}} \sin (100 \pi t) \text { ampere } \\ & e=\frac{1}{\sqrt{2}} \sin (100 \pi t+\pi / 3) \text { volt } \end{aligned} $$ The average power in Watts consumed in the circuit is
A millivoltmeter of $25 \mathrm{mV}$ range is to be converted into an ammeter of 25 A range. The value (in ohm) of necessary shunt will be
A magnetic needle suspended parallel to a magnetic field requires $\sqrt{3} \mathrm{~J}$ of work to turn it through $60^{\circ}$. The torque needed to maintain the needle in this position will be
If voltage across a bulb rated $220 \mathrm{~V}-100 \mathrm{~W}$ drops by $2.5 \%$ of its rated value, the percentage of the rated value by which the power would decrease is
In a coil of resistance $10 \Omega$, the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in weber is 
The electric field associated with an electro magnetic wave in vacuum is given by $\mathbf{E}=\mathbf{i}$ $40 \cos \left(k z-6 \times 10^8 t\right)$, where $E$, $z$ and $t$ are in volt/m, metre and second respectively. The value of wave vector $k$ is
A proton carrying $1 \mathrm{MeV}$ kinetic energy is moving in a circular path of radius $R$ in uniform magnetic field. What should be the energy of an $\alpha$-particle to describe a circle of same radius in the same field?
The power dissipated in the circuit shown in the figure is 30 Watt. The value of $R$ is 
A cell having an $\operatorname{emf} \varepsilon$ and internal resistance $r$ is connected across a variable external resistance $R$. As the resistance $R$ is increased, the plot of potential difference $V$ across $R$ is given by
The current $(I)$ in the inductance is varying with time according to the plot shown in figure.  Which one of the following is the correct variation of voltage with time in the coil?
An alternating electric field of frequency $v$, is applied across the dees (radius $=R$) of a cyclotron that is being used to accelerate protons (mass $=m$ ). The operating magnetic field $(B)$ used in the cyclotron and the kinetic energy $(K)$ of the proton beam, produced by it, are given by
Two similar coils of radius $R$ are lying concentrically with their planes at right angles to each other. The currents flowing in them are $I$ and $2 I$, respectively. The resultant magnetic field induction at the centre will be
In an electrical circuit $R, L, C$ and an $\mathrm{AC}$ voltage source are all connected in series. When $L$ is removed from the circuit, the phase difference between the voltage and the current in the circuit is $\pi / 3$. If instead, $C$ is removed from the circuit, the phase difference is again $\pi / 3$. The power factor of the circuit is