Electromagnetic Induction · Question 18

A long solenoid has 1000 turns. When a current of 4 A flows through it, the magnetic flux linked with each turn of the solenoid is 4 10-3 Wb. The self-inductance of the solenoid is

1. 2 H
2. 1 H
3. 4 H
4. 3 H

A uniform magnetic field is restricted within a region of radius r. The magnetic field changes with time at a rate d Bdt. Loop 1 of radius R > r encloses the region r and loop 2 of radius R is outside the region of magnetic field as shown in the figure. Then the e.m.f. generated is [figure]

1. zero in loop 1 and zero in loop 2
2. - d Bdt r2 in loop 1 and - d Bdt r2 in loop 2
3. - d Bdt R2 in loop 1 and zero in loop 2
4. - d Bdt r2 in loop 1 and zero in loop 2

An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron. What will be the direction of current, if any, induced in the coil ? [figure]

1. The current will reverse its direction as the electron goes past the coil
2. No current induced
3. abcd
4. adcb

A conducting square frame of side 'a' and a long straight wire carrying current I are located in the same plane as shown in the figure. The frame moves to the right with a constant velocity 'V'. The emf induced in the frame will be proportional to [figure]

1. 1(2x+a)2
2. 1(2x-a)(2x+a)
3. 1x2
4. 1(2x-a)2

A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in the figure. [figure] The potential difference developed across the ring when its speed is v, is

1. zero
2. Bv r22 and P is at higher potential
3. rBv and R is at higher potential
4. 2rBv and R is at higher potential

A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is

1. four times per revolution
2. six times per revolution
3. once per revolution
4. twice per revolution

A current of 2.5 A flows through a coil of inductance 5 H. The magnetic flux linked with the coil is

1. 0.5 Wb
2. 12.5 Wb
3. zero
4. 2 Wb

In a coil of resistance 10 , the induced current developed by changing magnetic flux through it, is shown in figure as a function of time. The magnitude of change in flux through the coil in weber is [figure]

1. 8
2. 2
3. 6
4. 4

A coil of resistance 400 is placed in a magnetic field. If the magnetic flux (Wb) linked with the coil varies with time t (sec) as = 50t2 + 4. The current in the coil at t = 2 sec is

1. 0.5 A
2. 0.1 A
3. 2 A
4. 1 A

The current (I) in the inductance is varying with time according to the plot shown in figure. [figure] Which one of the following is the correct variation of voltage with time in the coil ?

1. [figure]
2. [figure]
3. [figure]
4. [figure]