Current Electricity MCQs
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