1. The best suitable material for the heating element is
(a) Tungsten (b) Nichrome (c) Manganin (d) Carbon 2. Pure silicon is
(a) a p-type semiconductor (b) an n-type semiconductor (c) an intrinsic semiconductor (d) an extrinsic semiconductor
3. Impurity atoms to be added to pure silicon in order to make a p-type semiconductor belongs to
(a) Phosphorous (b) Boron (c) Antimony (d) Aluminium
4. Resistivity of a wire depends upon
(a) Material (b) Area (c) Length (d) All of these
5. If a ferromagnetic material is heated upto Curie temperature, it becomes
(a) Permanent magnet (b) Anti-ferromagnetic material (c) Diamagnetic material (d) Paramagnetic material
6. At absolute zero temperature, an intrinsic semiconductor behaves as
(a) a good conductor (b) a super conductor (c) an insulator (d) variable resistor
7. In an intrinsic semiconductor the Fermi level is
(a) closer to valence band. (b) closer to conduction band. (c) within the balance band. (d) midway between the valence and conduction bands.
8. The reluctance offered by a magnetic material is highest when it is
(a) Diamagnetic (b) Paramagnetic (c) Ferromagnetic (d) None of these
9. If temperature of a pure silicon specimen is increased, then
(a) only number of free electrons increase. (b) only number of free holes increase. (c) number of free holes and free electrons increases. (d) only number of free holes decrease.
10. Varnishes protect the insulating materials against
(a) dust and oil (b) moisture, dirt and oil (c) moisture and fire hazards (d) None of the above
11. If a 220 V heater is used on 110 V supply, the heat produced by it will be nearly
(a) one half (b) twice (c) one-fourth (d) four times
12. The reactance offered by a capacitor to an alternating current of frequency 50 Hz is 10 ohm. If frequency is increased to 100 Hz, the reactance will be
(a) 2.5 ohm (b) 5.0 ohm (c) 20.0 ohm (d) 40.0 ohm
13. The capacity of a battery is measured in
(a) Watts (b) Watt-hours (c) Amperes (d) Ampere-hours
14. If both the number of turns and core length of an inductive coil are doubled, then its self inductance will be
(a) halved (b) doubled (c) quadrupled (d) unaffected
15. Mutual inductance between two magnetically coupled coils depends on
(a) number of turns only (b) permeability of the core only (c) cross-sectional area of their common core only (d) All of the above
16. For an RLC series AC circuit, the current at series resistance is
(a) maximum at lagging power factor (b) maximum at leading power factor (c) maximum at unity power factor (d) minimum at unity power factor
17. If v = (a + jb) and i = (c + jd), then active power is given by
(a) ac + ad (b) ac + bd (c) bc – bd (d) ad + bc
18. If a capacitance is charged by a square wave current source, then the voltage across the capacitor will be
(a) Square wave (b) Step function (c) Triangular wave (d) Zero
19. The output voltage of a battery drops from 100 V with zero load current to 80 V when load current is 2 A. The internal resistance of the battery is
(a) 10 Ω (b) 20 Ω (c) 40 Ω (d) 50 Ω
20. A charge of 0.1 coulomb moves through a given point in every 0.05 seconds. The current flowing through the point is
(a) 2 mA (b) 5 mA (c) 2 A (d) 5 A
ANSWER :
1-B, 2-C, 3-B/D, 4-A, 5-D, 6-C, 7-D, 8-A, 9-C, 10-B, 11-C, 12-B, 13-D, 14-B, 15-D, 16-C, 17-B, 18-C, 19-A, 20-C
Weldon
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