Electro magnetic induction practice · Mixed difficulty

A wire of length $\mathrm{50}\,\,\mathrm{cm}$ moves with a velocity of $\mathrm{300}\,\,\mathrm{m - mi}{\mathrm{n}^{\mathrm{ - 1}}}$, perpendicular to a magnetic field. If the emf induced in the wire is $\mathrm{2}\,\mathrm{V}$, the magnitude of the field in telsa is

Choke coil works on the principle of

A short magnet is allowed to fall from rest along the axis of a horizontal conducting ring. The distance fallen by the magnet in one second may be

A thin circular ring of area $\mathrm{A}$ is held perpendicular to a uniform magnetic field of induction B. A small cut is made in the ring and a galvanometer is connected across the ends such that the total resistance of the circuit is $\mathrm{R}$. When the ring is suddenly squeezed to zero area, the charge flowing through the galvanometer is

The number of turns of primary and secondary coils of a transformer are $\mathrm{5}\,\,\mathrm{and}\,\mathrm{10}$ respectively and the mutual inductance of the transformer is $25\,\,henry$. Now the number of turns in the primary and secondary of the transformer are made $\mathrm{10}\,\,\mathrm{and}\,\mathrm{5}$ respectively. The mutual inductance of the transformer in $henry$ will be

The mutual inductance between two coils is $2.5 \mathrm{~H}.$ If the current in one coil is changed at the rate of $1 \mathrm{~As}^{-1},$ what will be the emf induced in the other coil?

The mutual inductance between two coils depends upon

Assertion: At any instant, if the current through an inductor is zero, then the induced emf may not be zero

Reason: An inductor tends to keep the flux (i.e. current) constant

An induced e.m.f. is produced when a magnet is plunged into a coil. The strength of the induced e.m.f. is independent of

Assertion : The quantity L/R possesses dimension of time.

Reason : To reduce the rate of growth of current through a solenoid, we should increase the time constant (L/R).

Current in a coil falls from 5.0 A to 1.0 A in 0.1 s. If an average emf of 200 V is induced, then self-inductance of the coil is

The magnetic flux linked with a coil is $\phi$ and the emf induced in it is $\mathrm{e}$

The emf induced in the secondary coil due to unit rate of change of current in the primary is called _______

If rotational velocity of a dynamo armature is doubled, then induced e.m.f. will become

A circular ring of diameter $\mathrm{20}\,\mathrm{cm}$ has a resistance of $0.01\,\,\mathrm{\Omega }$. The charge that will flow through the ring if it is turned from a position perpendicular to a uniform magnetic field of $\mathrm{2}.\mathrm{0}\,\mathrm{T}$ to a position to the field is about

A capacitor (without dielectric) is discharging through a resistor. At some instant a dielectric is inserted between the plates, then

$5\,\,cm$ long solenoid having $10\,\,ohm$ resistance and $5\,\,mH$ inductance is joined to a $10\,\,volt$ battery. At steady state the current through the solenoid in ampere will be

The current in a coil changes from 0 to $2 \mathrm{~A}$ in $0.05 \mathrm{~s}$. If the induced emf is $80 \mathrm{~V}$, the self-inductance of the coil is,

Assertion (A): Only a change in magnetic flux will maintain an induced current in a closed coil.

Reason (R): The presence of large magnetic flux through a coil maintains a current in the coil if the coil is continuous.

Two different coils have self inductance $\mathrm{L}_1=9 \mathrm{~mH}$ and $\mathrm{L}_2=3 \mathrm{~mH}$. At a certain instant, the current in the two coils in increasing at the same rate and the power supplied to the coils in also the same. The ratio of the energy stored in the two coils $\left(\mathrm{U}_1 / \mathrm{U}_2\right)$ at that instant is

Use of eddy currents is favoured in the following except

A $\mathrm{50}$ turns circular coil has a radius of $\mathrm{3}\,\mathrm{ cm}$, it is kept in a magnetic field acting normal to the area of the coil. The magnetic field $B$ increased from $\mathrm{0}\mathrm{.10}$ to $\mathrm{0}\mathrm{.35 T}$ in $\mathrm{2}\,\,\mathrm{millisecond}$. The average induced emf in the coil is

The inductance in a coil plays the same role as

A ring of radius a rotates with a constant angular velocity $\omega$ about its axis (passing through its centre and perpendicular to its plane). The ring is in $x-y$ plane. The potential difference induced in the ring would be zero, if uniform magnetic field is along

Consider the situation shown in figure. If the switch is closed and after some time it is opened again, the closed loop will show