1. 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
2. Heat in a conductor is produced on the passage of electric current due to
(a) reactance
(b) capacitance
(c) impedance
(d) resistance
Ans:
3. When one leg of parallel circuit is opened out the total current will
(a) reduce
(b) increase
(c) decrease
(d) become zero
Ans: c
4. 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
5. 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
6. 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
7. 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
8. 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
9. Resistance of carbon filament lamp as the applied voltage increases.
(a) increases
(b) decreases
(c) remains same
(d) none of the above
Ans: b
10. Bulbs in street lighting are all connected in
(a) parallel
(b) series
(c) series-parallel
(d) end-to-end
Ans: a
11. For testing appliances, the wattage of test lamp should be
(a) very low
(b) low
(c) high
(d) any value
Ans: c
12. Switching of a lamp in house produces noise in the radio. This is because switching operation produces
(a) arcs across separating contacts
(b) mechanical noise of high intensity
(c) both mechanical noise and arc between contacts
(d) none of the above
Ans: a
13. Sparking occurs when a load is switched off because the circuit has high
(a) resistance
(b) inductance
(c) capacitance
(d) impedance
Ans: b
14. Copper wire of certain length and resistance is drawn out to three times its length without change in volume, the new resistance of wire becomes
(a) 1/9 times
(b) 3 times
(e) 9 times
(d) unchanged
Ans: c
15. When resistance element of a heater fuses and then we reconnect it after removing a portion of it, the power of the heater will
(a) decrease
(b) increase
(c) remain constant
(d) none of the above
Ans: b
16. A field of force can exist only between
(a) two molecules
(b) two ions
(c) two atoms
(d) two metal particles
Ans: b
17. A substance whose molecules consist of dissimilar atoms is called
(a) semi-conductor
(b) super-conductor
(c) compound
(d) insulator
Ans: c
18. International ohm is defined in terms of the resistance of
(a) a column of mercury
(b) a cube of carbon
(c) a cube of copper
(d) the unit length of wire
Ans: a
19. Three identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be
(a) 9 times
(b) 1/9 times
(c) 1/3 times
(d) 3 times
Ans: b
20. Which method can be used for absolute measurement of resistances ?
(a) Lorentz method
(b) Releigh method
(c) Ohm's law method
(d) Wheatstone bridge method
Ans: d
