Railway Science (Physics-Electric Current and its Effects) (Part-V)

Total Questions: 50

41. Two bulbs A and B are connected in parallel to a 3 V source. If the ratio of resistance of bulb A to that of bulb B is 1 : 3. The ratio of the heat produced by bulb A to that of bulb B in a given time is: [RRC Group D 24/08/2022 (Morning)]

Correct Answer: (a) 3 : 1
Solution:

42. A current of 2.5 mA flows through a conductor having resistance 2Ω. The potential difference across the ends of the conductor is: [RRC Group D 24/08/2022 (Morning)]

Correct Answer: (a) 5 mV
Solution:

As per Ohm’s law, V = IR = 2.5 mA × 2 Ω = 5 mV.

43. When a potential difference of 50 V is applied across the terminals of an electrical appliance, a current of 5 A flows through it. If the potential difference is increased to 110 V, what will be the current drawn by the appliance? [RRC Group D 24/08/2022 (Afternoon)]

Correct Answer: (d) 11A
Solution:

As per Ohm’s Law:
V = IR ⇒ 50 = 5 × R
⇒ R = 10 Ω.
∴ I = V/R = 110/10 = 11 A.

44. Two resistors R1 and R2 with resistances 2Ω and 3Ω, respectively, are connected in series to a 15V battery source. The current across R₂ (in A) is: [RRC Group D 24/08/2022 (Evening)]

Correct Answer: (b) 3
Solution:

Given R₁ = 2 Ω , R₂ = 3 Ω , and V = 15 Volt If the resistances are connected in series, the current is the same across all resistances.
Now, equivalent resistance,
R = R₁+ R₂ = 2 Ω + 3 Ω = 5 Ω.
Using Ohm’s law, V = IR ⇒ I = V/R = 15 / 5 = 3 A. So the value of current flowing in R₂ = 3 A.

45. Two bulbs A and B are rated 100 W and 25 W respectively at a given voltage. Find the ratio of resistances of bulb A and bulb B. [RRC Group D 25/08/2022 (Morning)]

Correct Answer: (c) 1 : 4
Solution:

46. Two resistors A and B have resistances 5 ohm and 10 ohm, respectively. If they are connected in series to a voltage source of 5 V. The ratio of power developed in resistor A to that of power developed in resistor B will be: [RRC Group D 25/08/2022 (Afternoon)]

Correct Answer: (b) 1 : 2
Solution:

47. Two metallic wires A and B are made of the same material. Wire A has length I and radius r while wire B has length 2l and radius 2r. The ratio of the resistance of wire A to that of wire B is: [RRC Group D 25/08/2022 (Afternoon)]

Correct Answer: (b) 2 : 1
Solution:

48. An electric device draws a current of 5A when connected to a 220V supply. The power of the electric device is: [RRC Group D 25/08/2022 (Evening)]

Correct Answer: (a) 1.1 kW
Solution:

Voltage (V) = 220V,
Current (I) = 5 A
We know that P = V × I
P = 220 × 5 = 1100 watt = 1.1 kW.

49. Which of the following options gives the current and equivalent resistance of the circuit in respective order? [RRC Group D 26/08/2022 (Morning)]

Correct Answer: (d) 0.5 A, 12Ω
Solution:

50. Two resistances A and B of 10 Ω and 20 Ω respectively are connected in parallel with a 6V battery. The total energy supplied by the battery to the circuit in 1 second will be _______. [RRC Group D 26/08/2022 (Afternoon)]

Correct Answer: (d) 5.4 J
Solution: