42 practice sets · Page 2 of 3
Two identical coaxial coils P and Q carrying equal amount of current in the same direction are brought nearer. The current in
P increases while in Q decreases
Q increases while in P decreases
both P and Q increases
both P and Q decreases
Why is the core of a transformer laminated?
To prevent eddy currents
To prevent mutual induction
To prevent self induction
None of these.
In a coil of self-induction 5 H, the rate of change of current is 2 As-1. Then emf induced in the coil is
10 V
-10 V
5 V
-5 V
The north pole of a long bar magnet was pushed slowly into a short solenoid connected to a short galvanometer. The magnet was held stationary for a few seconds with the north pole in the middle of the solenoid and then withdrawn rapidly. The maximum deflection of the galvanometer was observed when the magnet was
moving towards the solenoid
moving into the solenoid
at rest inside the solenoid
moving out of the solenoid
A coil of 100 turns carries a current of 5 mA and creates a magnetic flux of 10-5 weber. The inductance is
0.2 mH
2.0 mH
0.02 mH
0.002 H
A coil having 500 sq. loops of side 10 cm is placed normal to magnetic flux which increases at a rate of 1 T/s. The induced emf is
0.1 V
0.5 V
1 V
5 V
The self inductance associated with a coil is independent of
current
induced voltage
time
resistance of a coil
When current in a coil changes from 5 A to 2 A in 0.1 s, average voltage of 50 V is produced. The self-inductance of the coil is
1.67 H
6 H
3 H
0.67 H
Two identical coaxial circular loops carry a current i each circulating in the same direction. If the loops approach each other, you will observe that the current in
each remains the same
one increases whereas that in the other decreases
each increases
each decreases
Two coils are placed closed to each other. The mutual inductance of the pair of coils depends upon
the material of the wires of the coils.
the currents in the two coils.
the rate at which currents are changing in the two coils.
relative position and orientation of two coils.
The laws of electromagnetic induction have been used in the construction of a
electric motor
generator
galvanometer
voltmeter
A magnet is moved towards a coil (i) quickly (ii) slowly, then the induced e.m.f. is
equal to both the cases
larger or smaller depending upon the radius of the coil
larger in case (i)
smaller in case (i)
Lenz's law is a consequence of the law of conservation of
energy
momentum
charge
mass
Two pure inductors each of self inductance L are connected in series, the net inductance is
L/2
L/4
L
2 L
The coils in resistance boxes are made from doubled insulated wire to nullify the effect of
pressure
self induced e.m.f.
heating
magnetism
The self inductance of a coil is a measure of
induced e.m.f.
induced current
electrical inertia
electrical friction
The polarity of induced emf is given by
Lenz's law
Fleming's right hand rule
Ampere's circuital law
Biot-Savart law
A coil of insulated wire is connected to a battery. If it is taken to galvanometer, its pointer is deflected, because
the number of turns in the coil of the galvanometer are changed
None of these
the induced current is produced
the coil acts like a magnet
According to Faraday's law of electromagnetic induction
magnetic field is associated with a moving charge.
None of these.
electric field is produced by time varying magnetic flux.
magnetic field is produced by time varying electric flux.
An induced e.m.f. is produced when a magnet is plunged into a coil. The strength of the induced e.m.f. is independent of
the resistivity of the wire of the coil
speed with which the magnet is moved
the strength of the magnet
number of turns of coil
