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 \(\omega\). The maximum value of the emf induced in it is:
1. \(\frac{NBA}{\omega}\)
2. \(NBAω\)
3. \(\frac{NBA}{\omega^{2}}\)
4. \(NBAω^{2}\)
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 \(t = 5~\text{s}\) 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 |