A coil of resistance 400 is placed in magnetic field. If the magnetic flux Φ (Wb) linked with the coil varies with time t (sec) as Φ = 50t2 +4.
The current in the coil at t= 2 s is
0.5 A
0.1 A
2 A
2 A
Two similar coils of radius R are lying concentrically with their planes at right angles to each other. The currents flowing in them are I and 2I, respectively. The resultant magnetic field induction at the centre will be
The potential energy of a particle in a force field is, where A and B are positive constants are r is the distance of a particle from the centre of the field. For stable equilibrium, the distance of a particle is
B/2A
2A/B
A/B
A/B
In an electrical circuit R, L, C and AC voltage source are all connected in series when L is removed from the circuit, the phase difference between the voltage and the current in the circuit is π/3. If instead, Cis removed from the circuit, the phase difference is again π/3. The power factor of the circuit is
1/2
1
1
A millivoltmeter of 25 mV range is to be converted into an ammeter of 25 A range. The value (in ohm) of necessary shunt will be
0.001
0.01
1
1
A compass needle which is allowed to move in a horizontal plane is taken to a geomagnetic pole. it
will become rigid showing no movement
will stay in any position
will stay in the north-south direction only
will stay in the north-south direction only
B.
will stay in any position
It will stay in any position at geomagnetic north and south poles.
The electric field associated with an electromagnetic wave in vacuum is given by E=i 40 cos (kz-6x108t), where E, z= and t are in volt/m, metre and second respectively. The value of wave vector k is
2 m-1
0.5 m-1
6 m-1
6 m-1
What is the flux through a cube of side a if a point charge of q is a one of its corner?
A ring is made of wire having a resistance Ro = 12Ω. Find the points A and B, as shown in the figure, at which a current carrying conductor should be connected so that the resistance R of the subcircuit between these points is equal to 8/3Ω
If voltage across a bulb rated 220 V -100W drops by 2.5% of its rated value, the percentage of the rated value by which the power would decrease is
20%
2.5%
5%
5%