Electromagnetism PYQ — Page 17

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

A bar magnet having a magnetic moment of $2 \times 10^4 \mathrm{JT}^{-1}$ is free to rotate in a horizontal plane. A horizontal magnetic field $\mathrm{B}=6 \times 10^{-4} \mathrm{~T}$ exists in the space. The work done in taking the magnet slowly from a direction parallel to the field to a direction $60^{\circ}$ from the field is

A conducting circular loop is placed in a uniform magnetic field $0.04 \mathrm{~T}$ with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at $2 \mathrm{~mm} / \mathrm{s}$. The induced emf in the loop when the redius is $2 \mathrm{~cm}$ is :

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

A student measures the terminal potential difference (V) of a cell (of emf $\varepsilon$ and internal) resistance $r$ ) as a function of the current (I) flowing through it. The slope and intercept of the graph between $\mathrm{V}$ and $\mathrm{I}$, then respectively equal to :

Under the influence of a uniform magnetic field, a charged particle moves with constant speed $\mathrm{V}$ in a circle of radius $R$. The time period of rotation of the particle :

The mean free path of electrons in a metal is $4 \times 10^{-8} \mathrm{~m}$. The electric field which can give on an average $2 \mathrm{eV}$ energy to an electron in the metal will be in unit of $\mathrm{Vm}^{-1}$

A current of $3 \mathrm{amp}$. flows through the $2 \Omega$ resistor shown in the circuit. The power dissipated in the $5 \Omega$ resistor is 

Curie temperature is the temperature above which

A circular disc of radius 0.2 meter is placed in a uniform magnetic field of induction linked with the disc is

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

The velocity of electromagnetic radiation in a medium of permittivity $\varepsilon_0$ and permeability $\mu_0$ is given by

The velocity of electromagnetic radiation in a medium of permittivity $\in_0$ and permeability $\mu_0$ is given by

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 

In an $A C$ circuit the emf (e) and the current (i) at any instant are given respectively by $e=E_0 \sin \omega t$ $i=I_0 \sin (\omega t-\phi)$ The average power in the circuit over one cycle of AC is

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

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 

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 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

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