Current Electricity  MCQs

MCQs of Current Electricity

Showing 51 to 60 out of 119 Questions
51.
Two wires which are made of the same material have the same cross-sectional area, but different lengths l1 and l2 are used as fuse wires. If same value of the current flowing through them, in the same time, which wire fuse early ?
(a) wire having length l1
(b) wire having length l2
(c) both will melt at the same time
(d) none of these
Answer:

Option (c)

52.
A and B are two electric bulbs with their ratings respectively 40 W, 110 V and 100 W and 110 V. Find their respective filament resistances. If the bulbs are connected in series with a supply of 220 V, which bulb will fuse ?
(a) RA = 22 Ω, RB = 100 Ω, bulb A
(b) RA = 160 Ω, RB = 50 Ω, both bulb A and B
(c) RA = 302.5 Ω, RB = 121 Ω, bulb A
(d) RA = 300 Ω, RB = 150 Ω, bulb B
Answer:

Option (c)

53.
The internal resistance of a cell of emf 4 V is 0·1 Ω. It is connected to a resistance of 3·9 Ω The voltage across the cell will be _____.
(a) 0·1 V
(b) 3·8 V
(c) 3·9 V
(d) 2 V
Answer:

Option (c)

54.
The ratio of cross- sectional areas of two conducting wires made up of same material and having same length is 1 : 2. What will be the ratio of heat produced per second in the wires, when same current is flowing in them ?
(a) 1 : 2
(b) 1 : 1
(c) 1 : 4
(d) 2 : 1
Answer:

Option (d)

55.
Two similar cells, whether joined in series or in parallel, have the same current through an external resistance of 2 Ω. The internal resistance of each cell is _____.
(a) 1·5 Ω
(b) 0·5 Ω
(c) 2 Ω
(d) 1 Ω
Answer:

Option (c)

56.
Two electric bulbs have ratings respectively of 25 W, 220 V and 100 W, 220 V. If the bulbs connected in series with a supply of 440 V, which bulb will fuse ?
(a) 100 W bulb
(b) 25 W bulb
(c) Both (A) and (B)
(d) None of the above
Answer:

Option (b)

57.
The maximum power dissipated in an external resistance R, when connected to a cell of emf E and internal resistance r, will be _____.
(a) E24
(b) E22r
(c) E23r
(d) E24r
Answer:

Option (d)

58.
The carbon resistor has three orange bands. The maximum value of resistance offered by the resistor will be _____.
(a) 49·6 kΩ
(b) 33 kΩ
(c) 39·6 kΩ
(d) 26·4 kΩ
Answer:

Option (c)

59.
Two wires of same material having lengths and in the radii in the ratio of 3 : 4 and 3 : 2 respectively, are connected in parallel with a potential source of 6 V. The ratio of currents flowing through them, I1 : I2 = _____.
(a) 1 : 3
(b) 1 : 2
(c) 3 : 1
(d) 2 : 1
Answer:

Option (c)

60.
Two wires of equal length and equal diameter and having resistivities ρ1 and ρ2 are connected in series. The equivalent resistivity of the combination is _____.
(a) ρ1+ρ2
(b) ρ1ρ2ρ1+ρ2
(c) ρ1+ρ22
(d) ρ1ρ2
Answer:

Option (c)

Showing 51 to 60 out of 119 Questions