One conducting U tube can slide inside another as shown in figure, maintaining electrical contacts between the tubes. The magnetic field B is perpendicular to the plane of the figure. if each tube moves towards the other at a constant speed V, then the emf induced in the circuit in terms of B,
B
-B
zero
zero
Two thin, long parallel wires separated by a distance ‘d’ carry a current of ‘i’ A in the same direction. They will
attract each other with a force of µ0i2/(2πd)
repel each other with a force of µ0i2/(2πd)
attract each other with a force of µ0i2(2πd2 )
attract each other with a force of µ0i2(2πd2 )
A charged ball B hangs from a silk thread S which makes an angle θ with a large charged conducting sheet P, as shown in the figure. The surface charge density σ of the sheet is proportional to
cos θ
cot θ
sin θ
sin θ
Two point charges + 8q and – 2q are located at x = 0 and x = L respectively. The location of a point on the x axis at which the net electric field due to these two point charges is zero is
2L
L/4
8L
8L
Two thin wires rings each having a radius R are placed at a distance d apart with their axes coinciding. The charges on the two rings are +q and –q. The potential difference between the centres of the two rings is
zero
zero
A parallel plate capacitor is made by stacking n equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C then the resultant capacitance is
(n − 1)C
(n + 1)C
C
C
Two concentric coils each of radius equal to 2π cm are placed at right angles to each other. 3 Ampere and 4 ampere are the currents flowing in each coil respectively. The magnetic induction in Weber/m2 at the centre of the coils will be (µ0 = 4π × 10−7 Wb/A-m)
12 × 10−5
10−5
5 × 10−5
5 × 10−5
A coil of inductance 300 mH and resistance 2Ω is connected to a source of voltage 2V. The current reaches half of its steady state value in
0.05 s
0.1 s
0.15 s
0.15 s
The self inductance of the motor of an electric fan is 10 H. In order to impart maximum power at 50 Hz, it should be connected to a capacitance of
4µF
8µF
1µF
1µF
An energy source will supply a constant current into the load of its internal resistance is
equal to the resistance of the load.
very large as compared to the load resistance.
zero
zero
B.
very large as compared to the load resistance.