1. 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
Ans: c
2. 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
3. An instrument which detects electric current is
known as
(a) voltmeter
(b) rheostat
(c) wattmeter
(d) galvanometer
Ans: d
4. 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
Ans: d
5. 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
Ans: b
6. 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
Ans: c
7. Which of the following material has nearly zero
temperature co-efficient of resistance?
(a) Manganin
(b) Porcelain
(c) Carbon
(d) Copper
Ans: a
8. You have to replace 1500 Q resistor in radio. You
have no 1500 Q resistor but have several 1000 Q ones which you would connect
(a) two in parallel
(b) two in parallel and one in
series
(c) three in parallel
(d) three in series
Ans: b
9. A closed switch has a
resistance of
(a) zero
(b) about 50 ohms
(c) about 500 ohms
(d) infinity
Ans: a
10. The hot resistance of the
bulb’s filament is higher than its cold resistance because the temperature
co-efficient of the filament is
(a) zero
(b) negative
(c) positive
(d) about 2 ohms per degree
Ans: c
11. Heat in a conductor is
produced on the passage of electric current due to
(a) reactance
(b) capacitance
(c) impedance
(d) resistance
Ans:
12. When one leg of parallel
circuit is opened out the total current will
(a) reduce
(b) increase
(c) decrease
(d) become zero
Ans: c
13. In a lamp load when more
than one lamp are switched on the total resistance of the load
(a) increases
(b) decreases
(c) remains same
(d) none of the above
Ans: b
14. Two lamps 100 W and 40 W
are connected in series across 230 V (alternating).
Which of the following
statement is correct ?
(a) 100 W lamp will glow
brighter
(b) 40 W lamp will glow
brighter
(c) Both lamps will glow
equally bright
(d) 40 W lamp will fuse
Ans: b
15. Resistance of 220 V, 100 W
lamp will be
(a) 4.84 Q
(b) 48.4 Q
(c) 484 ft
(d) 4840 Q
Ans: c
16. In the case of direct
current
(a) magnitude and direction of
current remains constant
(b) magnitude and direction of
current changes with time
(c) magnitude of current
changes with time
(d) magnitude of current
remains constant
Ans: a
17. When electric current
passes through a bucket full of water, lot of bubbling is observed. This
suggests that the type of supply is
(a) A.C.
(b) D.C.
(c) any of above two
(d) none of the above
Ans: b
18. Resistance of carbon
filament lamp as the applied voltage increases.
(a) increases
(b) decreases
(c) remains same
(d) none of the above
Ans: b
19. Bulbs in street lighting
are all connected in
(a) parallel
(b) series
(c) series-parallel
(d) end-to-end
Ans: a
20. For testing appliances, the
wattage of test lamp should be
(a) very low
(b) low
(c) high
(d) any value
Ans: c
