CBSE
Multiple Choice QuestionsWith the decrease of current in the primary coil from 2 amperes to zero value in 0.01s the emf generated in the secondary coil is 1000 volts. The mutual inductance of the two coils is
1.25 H
2.50 H
5.00 H
10.00 H
The core of any transformer is laminated so as to
reduce the energy loss due to eddy currents
make it light weight
make it robust & strong
D.C ammeter will get damaged
An engine has an efficiency of 1/6. When the temperature of sink is reduced by 62oC, its efficiency is doubled. The temperature of source will be
37o C
62o C
99o C
124o C
A circular coil with a cross-sectional area of 4 cm2 has 10 turns. It is placed at the center of a long solenoid that has 15 turns/cm and a cross-sectional area of IO cm2, as shown in the figure. The axis of the coil conicides with the axis of the solenoid. What is their mutual inductance?
7.54 μH
8.54 μH
9.54 μH
10.54 μH
Assertion: A spark occur when the poles of a switch when the switch is opened.
Reason: Current flowing in the conductor produces magnetic field.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Lenz law is consistent with conservation of
Energy
Mass
Charge
Momentum
Assertion: Transformers are used only in alternating current source not in direct current.
Reason: Only a.c. can be stepped up or down
by means of transformers.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
Mutual inductance M between two concentric coils of radii 1 m and 2 m is
A coil of wire of a certain radius has 100 turns and self inductance of 15 mH. The self inductance of a second of a second similar coil of 500 turns will be
75 mH
375 mH
15 mH
none of these
Assertion: Inductance coils are usually made of thick copper wire.
Reason: Induced current is more in wire having less resistance.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false
