Electro magnetic induction practice · Mixed difficulty

The approximate formula expressing the formula of mutual inductance of two thin coaxial loops of the same radius $a$ when their centers are separated by a distance $l$ with $l \gg a$ is

The mutual inductance of a pair of coils is $0.75\,\mathrm{H}$. If current in the primary coil changes from $0.5 \mathrm{~A}$ to zero in $0.01 \mathrm{~s}$ find average induced e.m.f. in secondary coil.

A wire loop that encloses an area of $20 \mathrm{~cm}^2$ has a resistance of $10 \Omega$. The loop is placed in a magnetic field of $2.4 T$ with its plane perpendicular to the field. The loop is suddenly removed from the field. How much charge flows pass a given point in the wire?

Two coil $\mathrm{A}$ and $\mathrm{B}$ have mutual inductance $2 \times 10^{-2}$ henry. If the current in the primary is $\mathrm{I}=5 \sin (10 \pi \mathrm{t})$ then the maximum value of e.m.f. induced in coil $\mathrm{B}$ is

The induced emf cannot be produced by:

The phenomenon called electromagnetic induction was first investigated by

Assertion(A): $L/R$ and $CR$ both have same dimensions.

Reason(R): ${L}/{R}$ and ${CR}$ are time constants.

Assertion: Magnetic flux is a vector qunatity

Reason: Value of magnetic flux can be positive, negative or zero.

Two coils are placed close to each other. The mutual inductance of the pair of coils depends upon

I. relative position and orientation of the two coils

II. the materials of the wires of the coils

III. the rates at which currents are changing in the two coils

Which of the above statements is/are correct?

A 10 m long horizontal wire extends from North-East to South-West. It is falling with a speed of $5.0\,\,\,m{s^{ - 1}}$ at right angles to the horizontal component of the earth’s magnetic field of $0.3 \times {10^{ - 4}}\,Wb/{m^2}.$ The value of the induced emf in wire is

A closed surface $S$ encloses a magnet of magnetic moment $2 \mathrm{~ml}$. The magnetic flux emerging from the surface is

A magnet is dropped down an infinitely long vertical copper tube

Assertion (A): Electromagnetic force is enormously strong as compared to gravitational force. Yet, gravity dominates in the large-scale phenomena (e.g. formation of galaxies).
Reason (R): Existence of positive and negative charges make matter mostly electrically neutral.
Which of the following is true?

A gold rod of length $l$ is accelerated in the horizontal direction with an acceleration $a_0$. The rod is held between two perfectly insulating clamps. Calculate the electric field set up in the rod. Take the mass of electron as $m$.

The magnetic potential energy stored in a certain induction is $\mathrm{25}{\mkern 1mu} {\mkern 1mu} \,mJ$, when the current in the inductors is $\mathrm{60}{\mkern 1mu} {\mkern 1mu} mA$. This inductors is of inductance

A cylindrical bar magnet is kept along the axis of a circular coil. If the magnet is rotated about its axis, then

Three identical ring move with the same speed on a horizontal surface in a uniform horizontal magnetic field normal to the planes of the rings. The first (A) slips without rolling, the second (B) rolls without slipping, and the third rolls with slipping

Two concentric circular coils have radius $R_1$ and $R_2$ such that $R_1 \ll R_2$. If a current is setup in the second coil then the mutual inductance of first coil with respect to second coil depends upon

An electric motor operates on a $50\,\,volt$ supply and a current of $12\,A$. If the efficiency of the motor is $\mathrm{30}\,\,\mathrm{\% }$, what is the resistance of the winding of the motor

An electric generator is based on ______

A long horizontal metallic rod with length along the east-west direction is falling under gravity. The potential difference between its two ends will

A coil has 1000 turns and $500\,\,\mathrm{c}{\mathrm{m}^2}$ as its area. The plane of the coil is placed of $2 \times {10^{ - 5}}\,\,\mathrm{web/}{\mathrm{m}^2}.$ The coil is rotated through ${180^0}$ in 0.2 seconds. The average emf induced in the coil, in milli volts is

A circular conducting loop of radius 10 cm is placed perpendicular to a uniform magnetic field of 1 T. if the magnetic field is made zero in a time interval of 0.1 s the emf induced in the loop during this time is.

A conducting rod of length $l$ is moving in a transverse magnetic field of strength $B$ with velocity $v$. The resistance of the rod is $R$. the current in the rod is

A magnet is allowed to move vertically through a resistance coil held horizontally. The
acceleration of the magnet is

Consider two identical, coaxial circular loops carrying a current i each, circulating in the same direction. If the loops approach each other

If a magnet is plugged into a coil, then the magnitude of induced emf does not depend upon

The self inductance of a long solenoid cannot be increased by

The self-inductance $L$ of a solenoid of length $l$ and area of cross-section $A$, with a fixed number of turns $N$ increases as

A field of strength $5 \times {10^4}/\pi$ Amp turns / meter acts at right angle to the coil of 50 turns of area ${10^{ - 2}}\,{m^2}$. The coil is removed from the field in 0.1 second. Then the induced emf in the coil is