A conducting rod AC of length 4l is rotated about point O in a uniform magnetic field directed into the paper. If AO = l and OC = 3l, then:
1.
2.
3.
4.
The graph gives the magnitude \(B(t)\) of a uniform magnetic field that exists throughout a conducting loop, perpendicular to the plane of the loop. Rank the five regions of the graph according to the magnitude of the emf induced in the loop, greatest first:
1. | \(b > (d = e) < (a = c)\) |
2. | \(b > (d = e) > (a = c)\) |
3. | \(b < d < e < c < a\) |
4. | \(b > (a = c) > (d = e)\) |
A square loop of side 5 cm enters a magnetic field with 1 cms-1. If the front edge enters the magnetic field at t = 0, then which graph best depicts emf?
1. | 2. | ||
3. | 4. |
A coil having number of turns N and cross-sectional area A is rotated in a uniform magnetic field B with an angular velocity . The maximum value of the emf induced in it is:
1.
2.
3.
4.
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 x 10-3 Wb. The self-inductance of the solenoid is:
1. 3 H
2. 2 H
3. 1 H
4. 4 H
A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is:
1. | Twice per revolution | 2. | Four times per revolution |
3. | Six times per revolution | 4. | Once per revolution |
A coil has 500 turns and the flux through the coil is \(\phi=3t^{2} +4t+9\) milliweber. The magnitude of induced emf between the ends of the coil at t = 5 s is:
1. 34 millivolt
2. 17 volt
3. 17 millivolt
4. 34 volt
The current I in an inductance coil varies with time t according to the graph shown in the figure. Which one of the following plots shows the variation of voltage in the coil with time?
1. | 2. | ||
3. | 4. |
A bar magnet is released along the vertical axis of the conducting coil. The acceleration of the bar magnet is:
1. | greater than g. | 2. | less than g. |
3. | equal to g. | 4. | zero. |
Work done in increasing the current through a solenoid from 0 to 2 A is 20 J. Work done in increasing the current from 4 A to 6 A is:
1. | 100 J | 2. | 60 J |
3. | 80 J | 4. | 120 J |