CBSE
Multiple Choice QuestionsThe magnetic flux linked with a coil at any instant t is given by the equation : = 5t3 − 100t + 300. The magnitude of emf induced in the coil after 3 s is
10 V
20 V
35 V
70 V
In 0.1 s, the current in a coil increases from 1 A to 1.5 A. If inductance of coil is 60 mH, then induced current in external resistance of 3Ω will be
1 A
0.5 A
0.2 A
0.1 A
If a coil of 40 turns and area 4.0 cm2 is suddenly removed from a magnetic field, it is observed that a charge of 2.0 x 10-4 C flows into the coil. If the resistance of the coil is 80 Ω, the magnetic flux density in Wb/m2 is
0.5
1.0
1.5
2.0
The magnetic flux linked with the coil varies with time as = 3 t2 + 4 t + 9. The magnitude of the induced emf at 2 s is
9 V
16 V
3 V
4 V
A coil having an inductance of 0.5 H carries a current which is uniformly varying from 0 to 10 A in 2s. The emf (in volts) generated in the coil is
10
5
2.5
1.25
Lenz's law of electromagnetic induction corresponds to the
law of conservation of charge
law of conservation of energy
law of conservation of momentum
law of conservation of angular momentum
The current through a coil of self-inductance L = 2mH is given by i = t2e-t at time t. How long it will take to make the emf zero ?
1 s
2 s
3 s
4 s
The magnetic flux through a loop of resistance 10 Ω is given by (=5t2 − 4t+ 1 Wb). How much current is induced in the loop after 0.2 s ?
0.4 A
0.2 A
0.04 A
0.02 A
The magnetic flux linked with a coil satisfies the relation Wb, where t is the time in second. The emf induced in the coil at t = 2 s is
22 V
18 V
16 V
40 V
A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when
frequency of the AC source is decreased
number of turns in the coil is reduced
a capacitance of reactance XC =XL is included in the same circuit
an iron rod is inserted in the coil
