Electromagnetism PYQ — Page 17

Three concentric spherical shells have radii $a, b$ and $c(a < b < c)$ and have surface charge densities $\sigma,-\sigma$ and $\sigma$ respectively. If $V_A, V_B$ and $V_C$ denote the potentials of the three shells, then for $c=a+b$, we have

Under the influence of a uniform magnetic field, a charged particle moves with constant speed $v$ in a circle of radius $R$. The time period of rotation of the particle

The electric field part of an electromagnetic wave in a medium is represented by \(\begin{aligned} & E_x=0 \\ & E_y=2.5 \mathrm{NC}^{-1} \cos \left[\left(2 \pi \times 10^6 \mathrm{rad} \mathrm{s}^{-1}\right) \mathrm{t}-\left(\pi \times 10^{-2} \mathrm{rad} \mathrm{m}^{-1}\right) \mathrm{x}\right] \\ & E_z=0\end{aligned}\) The wave is

A galvanometer having a coil resistance of $60 \Omega$ shows full scale deflection when a current of 1.0 A passes through it. It can be converted into an ammeter to read currents upto $5.0 \mathrm{~A}$ by

Three capacitors each of capacitance $C$ and of breakdown voltage $\mathrm{V}$ are joined in series. The capacitance and breakdown voltage of the combination will be :

The magnetic force acting on a charged particle of charge $-2 \mu \mathrm{C}$ in a magnetic field of $2 \mathrm{~T}$ acting in $y$ direction, when the particle velocity is $(2 \hat{\mathrm{i}}+3 \hat{\mathrm{j}}) \times 10^6 \mathrm{~ms}^{-1}$ is

See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it? 

Curie temperatures is the temperature above which

A thin conducting ring of radius $\mathrm{R}$ is given a charge $+\mathrm{Q}$. The electric field at the centre $\mathrm{O}$ of the ring due to the charge on the part $\mathrm{AKB}$ of the ring is $\mathrm{E}$. The electric field at the centre due to the charge on the part $\mathrm{ACDB}$ of the ring is 

A particle mass $m$, charge $Q$ and kinetic energy $T$ enters a transverse uniform magnetic field of induction $\overrightarrow{\mathbf{B}}$. After 3 s the kinetic energy of the particle will be

The electric potential at a point in free space due to a charge $\mathrm{Q}$ coulomb is $\mathrm{Q} \times 10^{11}$ volts. The electric field at that point is

In an a.c. circuit the e.m.f. (e) and the current (i ) at any instant are given respectively by $$ \begin{aligned} & e=E_0 \sin \omega t \\ & i=I_0 \sin (\omega t-\phi) \end{aligned} $$ The average power in the circuit over one cycle of a.c. is

A closed loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments $P S, S R$ and $R Q$ are $F_1, F_2$ and $F_3$ respectively and are in the plane of the paper and along the directions shown, the directions shown, the force on the segment $Q P$ is 

A particle of mass $\mathrm{m}$, charge $\mathrm{Q}$ and kinetic energy $\mathrm{T}$ enters a transverse uniform magnetic field of induction $\vec{B}$. After 3 seconds the kinetic energy of the particle will be

The energy required to charge a parallel plate condenser of plate separation $d$ and plate area of cross-section A such that the uniform electric field between the plates is E, is

The energy required to charge a parallel plate condenser of plate separation d and plate area of cross-section $A$ such that the uniform electric field between the plates is $E$, is

A cell can be balanced against $110 \mathrm{~cm}$ and $100 \mathrm{~cm}$ of potentiometer wire, respectively with and without being short circuited through a resistance of $10 \Omega$. Its internal resistance is

A thin conducting ring of radius $R$ is given a charge $+Q$. The electric field at the centre $O$ of the ring due to the charge on the part $A K B$ of the ring is $E$. The electric field at the centre due to the charge on the part $A C D B$ of the ring is 

A galvanometer of resistance $50 \Omega$ is connected to a battery of $3 \mathrm{~V}$ along with a resistance of $2950 \Omega$ in series. A full scale deflection of 30 divisions is obtained in the galvanometer. In order to reduce this deflection to 20 divisions, the resistance in series should be

In the circuit shown, the current through the $4 \Omega$ resistor is $1 \mathrm{amp}$ when the points $P$ and $\mathrm{M}$ are connected to a d.c. voltage source. The potential difference between the points $M$ and $N$ is 

A cell can be balanced against $110 \mathrm{~cm}$ and $100 \mathrm{~cm}$ of potentiometer wire, respectively with and without being short circuited through a resistance of $10 \Omega$ Its internal resistance is

A long solenoid has 500 turns. When a current of 2 ampere is passed through it, the resulting magnetic flux linked with each turn of the solenoid is $4 \times 10^{-3} \omega \mathrm{b}$. The selfinductance of the solenoid is

A closed loop PQRS carrying a current is placed in a uniform magnetic field. If the magnetic forces on segments PS, SR and RQ are $F_1, F_2$ and $F_3$ respectively and are in the plane of the paper and along the directions shown, the force on the segment QP is

A circular disc of radius $0.2 \mathrm{~m}$ is placed in a uniform magnetic field of induction $\frac{1}{\pi}\left(\frac{W b}{m^2}\right)$ in such a way that its axis makes an angle of $60^{\circ}$ with $\overrightarrow{\mathbf{B}}$. The magnetic flux linked with the disc is