Basic Electrical mcq (1-20)

1. The S.I. unit of power is
(a) Henry
(b) coulomb
(c) watt✔
(d) watt-hour

2. Electric pressure is also called
(a) resistance
(b) power
(c) voltage✔
(d) energy

3. The substances which have a large number of free electrons and offer a low resistance are called
(a) insulators
(b) inductors
(c) semi-conductors
(d) conductors✔

4. Out of the following which is not a poor conductor ?
(a) Cast iron
(b) Copper✔
(c) Carbon
(d) Tungsten

5. Out of the following which is an insulating material ?
(a) Copper
(b) Gold
(c) Silver
(d) Paper✔

6. The property of a conductor due to which it passes current is called
(a) resistance
(b) reluctance
(c) conductance✔
(d) inductance

7. Conductance is reciprocal of
(a) resistance✔
(b) inductance
(c) reluctance
(d) capacitance

8. The resistance of a conductor varies inversely as
(a) length
(b) area of cross-section✔
(c) temperature
(d) resistivity

9. With rise in temperature the resistance of pure metals
(a) increases✔
(b) decreases
(c) first increases and then decreases
(d) remains constant

10. With rise in temperature the resistance of semi-conductors
(a) decreases✔
(b) increases
(c) first increases and then decreases
(d) remains constant

11. The resistance of a copper wire 200 m long is 21 Q. If its thickness (diameter) is 0.44 mm, its specific resistance is around
(a) 1.2 x 10~8 Q-m
(b) 1.4 x 10~8 Q-m
(c) 1.6 x 10″”8 Q-m✔
(d) 1.8 x 10″8 Q-m

12. Three resistances of 10 ohms, 15 ohms and 30 ohms are connected in parallel.
The total resistance of the combination is
(a) 5 ohms✔
(b) 10 ohms
(c) 15 ohms
(d) 55 ohms

13. An instrument which detects electric current is known as
(a) voltmeter
(b) rheostat
(c) wattmeter
(d) galvanometer✔

14. In a circuit a 33 Q resistor carries a current of 2 A. The voltage across the resistor is
(a) 33 V
(b) 66 v✔
(c) 80 V
(d) 132 V

15. A light bulb draws 300 mA when the voltage across it is 240 V. The resistance of the light bulb is
(a) 400 Q
(b) 600 Q
(c) 800 Q✔
(d) 1000 Q

16. The resistance of a parallel circuit consisting of two branches is 12 ohms. If the resistance of one branch is 18 ohms, what is the resistance of the other ?
(a) 18 Q
(b) 36 Q✔
(c) 48 Q
(d) 64 Q

17. Four wires of same material, the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25 Q. If the same four wires are connected is series the effective resistance will be
(a) 1 Q
(b) 2 Q
(c) 3 Q
(d) 4 Q✔

18. A current of 16 amperes divides between two branches in parallel of resistances 8 ohms and 12 ohms respectively. The current in each branch is
(a) 6.4 A, 6.9 A
(b) 6.4 A, 9.6 A✔
(c) 4.6 A, 6.9 A
(d) 4.6 A, 9.6 A

19. Current velocity through a copper conductor is
(a) the same as propagation velocity of electric energy
(b) independent of current strength
(c) of the order of a few ^.s/m✔
(d) nearly 3 x 108 m/s

20. Which of the following material has nearly zero temperature co-efficient of resistance?
(a) Manganin✔
(b) Porcelain
(c) Carbon
(d) Copper