IIT JEE MCQ Quiz Hub

1. If in a galvanometer the coil is wound on a bad conductor the eddy current will be
zero
maximum
minimum
50% of the actual value

2. Eddy currents are also known as
Focault currents
Faraday currents
Huygen currents
Franklin currents

3. Lenz s law gives the
magnitude of induced e. m. f.
magnitude of induced current
direction of current/emf induced
None of these

4. If an e. m. f. of 300 micro volts is induced in a coil when current in it changes from 13 amperes to 7 amperes in 0.5 sec then the value of the self inductance of the coil will be25 micro henry20 micro henry27 micro henry
25 micro henry
20 micro henry
27 micro henry
17 micro henry

5. A bar magnet falls through a metal ring. The acceleration will be
equal to g
less than g
greater than g
zero

6. The laws of electromagnetic induction are the contribution of
Faraday
Maxwell
Lawrence
Hall

7. L / R has the dimensions ofhenrytime
mass
length
henry
time

8. The principle of eddy currents is used in
galvanometer
speedometer
pyrometer
barometer

9. A transformer is used to light a 100W and 110 V lamp from a 230 V mains If the main current is 05 A the efficiency of the transformer is
50%
20%
87%
67%

10. When power is drawn from the secondary coil of the transformer the dynamic resistance
remains same
decreases
increases
fluctuates.

11. A 20V ac is applied to a circuit consisting of a resistance and a coil with negligible resistance. If the voltage across the resistance is 12 V the voltage across the coil is10 V8 V6 V
16 V
10 V
8 V
6 V

12. An AC voltmeter reads 20 V across a resistor 30 V across an inductor and 15 V across a capacitor in LCR series circuit In this case the supply voltage will be
100 V
60 V
50 V
25 V

13. The S.I. unit of magnitude flux is
Maxwell
Tesla
Weber
Henry

14. The coil of a moving coil galvanometer is wound over metallic frames so that due to eddy currents the motion
remains the same
is damped
undamped
is made oscillatory

15. Electromagnetic induction is the underlying phenomenon in the construction of
galvanometer
pyrometer
pyrometer
generator

16. The property of an electric circuit by virtue of which any change in the magnetic flux linked with it induces an e m f in it is called
self-inductance
conductance
mutual induction
trans-conductance

17. Lenzs law is a consequence of the law of conservation ofmassenergy
mass
energy
momentum
charge

18. The frequency of ac in India is
50 Hz
50 kHz
1420 MHz
60 kHz

19. The alternating voltage which we use in house has a peak value of nearly
220 V
280 V
311 V
300 V

20. A step down transformer reduces 200 V to 110 V. The primary draws 5 amp. of current and secondary supplies 9 ampere. The efficiency of transformer is90%80%60%70%
90%
80%
60%
70%