Electro magnetic induction practice · Medium

Lenz’s law is statement of

In a dc motor, induced e.m.f. will be maximum

The dimensions of self inductance are

A wire of length $2.5 \mathrm{~km}$ and resistance $35 \Omega$ has fallen from a height of $10 \mathrm{~m}$ in earth's horizontal field of $2 \times 10^{-5} \mathrm{~T}.$ The current through the wire is

Energy associated with a moving charge is due to

Use of eddy currents is done in the following expect

We can reduce eddy currents in the core of the transformer

The inductance of a coil is $L = 10\,\,\mathrm{H}$ and resistance $R = 5\,\,\mathrm{\Omega }$. If applied voltage of battery is $\mathrm{10 V}$ and it switches off in $\mathrm{1 \,milli\,second}$, find induced emf of inductor

Assertion: Induced emf will always occur when ever there is change in magnetic flux.

Reason: Current always induces whenever there is change in magnetic flux.

The coupling coefficient of the perfectly coupled coil is:

Two different loops are concentric and lie in the same plane. The current in the outer loop is clockwise and increasing with time. The induced current in the inner loop then, is

The average power dissipated in a pure inductance is

Statement I: A flexible wire loop of irregular shape carrying current when placed in a uniform external magnetic field acquires circular shape.

Statement II: Any current carrying loop when placed in external magnetic field tries to acquires minimum energy and hence maximum magnetic flux and for a given perimeter circular shape is having greatest area.

A uniformly wound solenoidal coil of self inductance $1.8 \times {10^{ - 4}}$ H and resistance 6 Ω is broken up into two identical coils. These identical coils are then connected in parallel across a 12 V battery of negligible resistance. The time constant of the current in the circuit 

Assertion : The coils in the resistance boxes are made by doubling the wire.
Reason :When two coils are wound on each other, the mutual inductance is zero.

A rectangular, a square, a circular and an elliptical loop, all in the $\left( {x - y} \right)$ plane, are moving out of a uniform magnetic field with a constant velocity $\vec V = v\vec i$ . The magnetic field is directed along the negative $z$-axis direction. The induced $emf$, during the passage of these loops, out of the field region, will not remain constant for

Lenz’s law is a corollary of the law of conservation of

Two pure inductors each of self inductance $\text{L}$ are connected in series, the net inductance is

Three solenoid coils of same dimension, same number of turns and same number of layers of winding are taken. Coil $\mathrm{1}$ with inductance ${L_1}$ was wound using a $\mathrm{Mn}$ wire of resistance $\mathrm{11}\,\,\mathrm{\Omega }{m^{ - 1}}$;Coil $\mathrm{2}$ with inductance ${L_2}$ was wound using the similar wire but the direction of winding was reversed in each layer; Coil $\mathrm{3}$ with inductance ${L_3}$ was wound using a superconducting wire. The self-inductance of the Coils ${L_1},{L_2},{L_3}$ are

A square current carrying loop is changed to a circular loop in time $t_1$. Then

S-I: Induced e.m.f. tries to keep the energy conserved.

S-II: An e.m.f can be induced between the two ends of a straight copper wire when it is moved through a uniform magnetic field.

A small coil is introduced between the poles of an electromagnet so that its axis coincides with the magnetic field direction. The number of turns is n and the cross sectional area of the coil is $A$. When the coil turns through ${180^0}$ about its diameter, the charge flowing through the coil is $Q$. The total resistance of the circuit is $R$. What is the magnitude of the magnetic induction

A coil having 500 square loop each of side 10 cm is placed normal to a magnetic flux which increases at the rate of 1.0 tesla/second. The induced e.m.f in volts is

A coil having an inductance of $0.5\,\,H$ carries a current which is uniformly varying from zero to $\mathrm{10}\,\,\mathrm{ampere}$ in $\mathrm{2}\,\,\mathrm{second}$. The e.m.f. (in volts) generated in the coil is

A coil having an area $2{\mkern 1mu} \,{\mkern 1mu} {m^2}$ is placed in a magnetic field which changes from $1\,\,wb/{m^2}$ to $4\,\,wb/{m^2}$ in an interval of 2 second. The average e.m.f. induced in the coil will be

If the current through a coil changes from $1 \mathrm{~A}$ to $3 \mathrm{~A}$ in $0.02 \mathrm{~s}$ to produce an emf of $6 \mathrm{~V}$, then the self-inductance of the coil is

A boat is moving due east in a region where the earth’s magnetic field is $5.0 \times {10^{ - 5}}\,\,\mathrm{N}{\mathrm{A}^{ - 1}}{\mathrm{m}^{ - 1}}$ due north and horizontal. The boat carries a vertical aerial $1{\mkern 1mu} \mathrm{2}\,\mathrm{m}$ long. If the speed of the boat is $\mathrm{1}\mathrm{.50}\,\,\mathrm{m}{\mathrm{s}^{ - 1}}$, the magnitude of the induced emf in the wire of aerial is

As a result of change in the magnetic flux linked to the closed loop shown in the fig, an e.m.f. V volt is induced in the loop. The work done (joule) in taking a charge $\mathrm{Q}$ coulomb once along the loop is

Two identical coaxial circular loops carry a current $i$ each circulating in the same direction. As the loops are moved away from each other

An inductor is connected to a battery through a switch induced emf is $\mathrm{e}_1$ when the switch is pressed and $\mathrm{e}_2$ when the switch is opened. Then