Self inductances of two uncoupled coils are 40 mH and 90mH. Their mutual inductance is
1. 60 mH
2. 130 mH
3. 50 mH
4. Zero
Magnetic flux through a circuit of resistance \(20~\Omega\) is changed from \(20\) Wb to \(40\) Wb in \(5\) ms. The charge passed through the circuit during this time is:
1. \(1\) C
2. \(2\) C
3. zero
4. \(0.5\) C
A long straight conductor, carrying current I, is fixed on a smooth plane. A circular loop is placed on the same plane as shown in the figure. If the current I through the wire is increasing, then the loop will move towards:
1. Right
2. Left
3. Up
4. Down
Two coils have a mutual inductance of \(5\) mH. The current changes in the first coil according to the equation \(I=I_{0}\cos\omega t,\) where \(I_{0}=10~\text{A}\) and \(\omega = 100\pi ~\text{rad/s}\). The maximum value of emf induced in the second coil is:
1. \(5\pi~\text{V}\)
2. \(2\pi~\text{V}\)
3. \(4\pi~\text{V}\)
4. \(\pi~\text{V}\)
A circular loop is placed near a current-carrying conductor as shown. If the current in the straight conductor is decreasing, then the direction of the induced current in the loop is
1. Clockwise
2. Anticlockwise
3. Into the page
4. Out of the page
Two rails of a railway track insulated from each other on the ground are connected to a millivoltmeter. The reading of millivoltmeter when the train travels at a speed of 20m/s along the track is (Given: Bv = 0.210-4 Wb/m2 and distance between the rails is 1m)
1. 10 mV
2. 0.4 mV
3. 40 mV
4. 4 mV
1. | \(5\) H | 2. | \(2.5\) H |
3. | \(1.5\) H | 4. | \(2\) H |
Self-inductance of primary and secondary of a perfectly coupled coil is 40 mH and 90mH respectively. Coefficient of mutual induction between them is
1. 65 mH
2. 50 mH
3. 130 mH
4. 60 mH
A conducting square loop of side L and resistance R moves in its plane with a uniform velocity v perpendicular to one of its sides. A constant magnetic field B exists as shown in the figure. Mechanical power required to maintain its uniform velocity is
1.
2.
3.
4. Zero
A conducting disc of radius r rotates about its axis with an angular speed in a uniform magnetic field B perpendicular to the plane of the disc as shown. A resistance R is connected between centre and rim of the disc, then-
1. No e.m.f. will induce across the resistance
2. E.m.f. will induce and A is at high potential
3. Current in resistance will flow from A to B
4. Resistance becomes hot due to Joule's heating