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

Total Questions: 31

1. An electric lamp, having resistance 40 ohm, and conductor of 8 ohm is connected in series with a 12V battery. What is the total resistance of the circuit [RRB Group D 15/10/2018 (Evening)]

Correct Answer: (c) 48 ohm
Solution:

Total resistance (in series) = Resistance of lamp + Resistance of conductor = (40 + 8) = 48 Ω.

2. A house consumed 250 units of energy in a month. How much will this energy be in joules? [RRB Group D 15/10/2018 (Evening)]

Correct Answer: (c) 9 x 10⁸ J
Solution:

Energy consumed by certain households in a month (E)= 250 units = 250 kWh.
E = 250 units of energy = 250 × 3.6 × 10⁶ = 9 × 10⁸ J.

3. The work done between two points having the potential of 12 V is 36 J. The electric charge flowing between those points is __________ . [RRB Group D 16/10/2018 (Morning)]

Correct Answer: (c) 3 C
Solution:

Work (W) = Potential difference (V) × Charge (Q)
Given : Potential difference (V) = 12 V, Work done (W) = 36 J
36 J = Q × 12 V ⇒ Q = 36J/12V = 3 C.

4. A wire with 7 Ω resistance is doubled over it. Calculate the new resistance of the wire. [RRB Group D 16/10/2018 (Afternoon)]

Correct Answer: (c) 1.75 Ω
Solution:

5. A 8 Ω resistance wire is doubled on it. Calculate the new resistance of the wire. [RRB Group D 16/10/2018 (Evening)]

Correct Answer: (d) 2.00 Ω
Solution:

6. How much work is done in moving a charge of 4 C across two points having a potential difference of 11V ? [RRB Group D 22/10/2018 (Morning)]

Correct Answer: (d) 44 J
Solution:

The work done (W) in moving a charge (Q) across a potential difference (V) is given by the equation : W = V × Q W = 11V × 4C ⇒ W = 44 J.

7. A certain household has consumed 9 × 10⁸ J of energy in a month. How much energy is this in units ? [RRB Group D 22/10/2018 (Afternoon)]

Correct Answer: (a) 250 units
Solution:

8. If the current is 10 A and resistance 50 Ω, find the potential difference. [RRB Group D 23/10/2018 (Morning)]

Correct Answer: (d) 500 V
Solution:

Given: I = 10A and R = 50Ω.
As per Ohm’s Law : V = IR.
V = (10A) × (50Ω) = 500 V.

9. What is the work done in transferring a charge of 5 C between two points having a potential difference of 14 V? [RRB Group D 23/10/2018 (Morning)]

Correct Answer: (c) 70 J
Solution:

Given : Q = 5C and V = 14V
W = Q × V
W = (5 C) × (14 V) = 70 J.

10. What is the work done in passing a charge of 5 C between two points having a potential difference of 15 V? [RRB Group D 23/10/2018 (Afternoon)]

Correct Answer: (c) 75 J
Solution:

Given : Potential difference (PD) = 15 V,
Charge (Q)= 5C.
∵ Work done = Potential difference × Charge = 15 V × 5C = 75 J.