41. If a wire conductor of 0.2 ohm resistance is doubled in length, its resistance becomes
(a) 0.4 ohm
(b) 0.6 ohm
(c) 0.8 ohm
(d) 1.0 ohm
Ans: a
42. Three 60 W bulbs are in parallel across the 60 V power line. If one bulb burns open
(a) there will be heavy current in the main line
(b) rest of the two bulbs will not light
(c) all three bulbs will light
(d) the other two bulbs will light
Ans: d
43. The four bulbs of 40 W each are connected in series swift a battery across them, which of the following statement is true ?
(a) The current through each bulb in same
(b) The voltage across each bulb is not same
(c) The power dissipation in each bulb is not same
(d) None of the above
Ans: a
44. Two resistances Rl and Ri are connected in series across the voltage source where Rl>Ri. The largest drop will be across
(a) Rl
(b) Ri
(c) either Rl or Ri
(d) none of them
Ans: a
45. What will be energy used by the battery if the battery has to drive 6.28 x 1018 electrons with potential difference of 20 V across the terminal ?
(a) 5 joules
(b) 10 joules
(c) 15 joules
(d) 20 joules
Ans:
46. A closed switch has a resistance of
(a) zero
(b) about 50 ohms
(c) about 500 ohms
(d) infinity
Ans: a