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

Total Questions: 31

21. The resistors of values 3Ω, 6Ω and 15Ω are connected in parallel. What will be equivalent resistance in the circuit ? [RRB Group D 06/12/2018 (Morning)]

Correct Answer: (d) 1.7
Solution:

22. The boiling point of an alcohol is 78 °C. What is the temperature in Kelvin scale? [RRB ALP Tier - I (09/08/2018) Evening]

Correct Answer: (d) 351K
Solution:

The relationship between Kelvin scale and Celsius scale of temperature can be written as: Temperature on kelvin scale = Temperature on Celsius scale + 273 Temperature on kelvin scale = 78 + 273 Temperature on kelvin scale = 351 k

23. Two identical resistors, each of 10 Ω, are connected in parallel. This combination, in turn, is connected to a third resistor of 10 Ω. The equivalent resistance of the combination is_________. [RRB ALP Tier - I (13/08/2018) Morning]

Correct Answer: (c) 15 Ω
Solution:

24. In a hydrogen atom, an electron moves in an orbit of radius 5.0 × 10⁻¹¹m with a speed of 2.2 × 10⁶ m/s. What is the equivalent current? (Electronic charge = 1.6 × 10⁻¹⁹ C) [RRB ALP Tier - I (14/08/2018) Afternoon]

Correct Answer: (a) 1.12 mA
Solution:

25. If ‘I’ is the current through a wire and ‘e’ is the charge of an electron, then the number of electrons crossing in ‘t’ seconds will be given by: [RRB ALP Tier - I (17/08/2018) Morning]

Correct Answer: (b) It/e
Solution:

26. Assuming that the charge of an electron is 1.6 x 10⁻¹⁹ C, the number of electrons passing through a section of wire per second when the wire carries a current of 1 A is: [RRB ALP Tier - I (17/08/2018) Evening]

Correct Answer: (c) 6.25 × 10¹⁸
Solution:

27. If two Coulomb of charge flows through any cross-section of a conductor in one second, what will be the current flowing through it? [RRB ALP Tier - I (20/08/2018) Morning]

Correct Answer: (d) 2 Ampere
Solution:

I = 𝑄/t where I
= Current, Q = charge, t = time;
⇒ I = 𝑄/t = 2/1 = 2 Ampere

28. A charge of 2 C passes from one point to the other in a circuit. If the potential difference between the two points is 5 V, the amount of work done is: [RRB ALP Tier - I (21/08/2018) Afternoon]

Correct Answer: (a) 10 J
Solution:

The amount of work done to move a unit charge from a point to another point in a space where an electric field is present is called the electric potential difference.

29. Two particles with charges q₁ and q₂ are kept at a certain distance to exert force F on each other. If the distance is reduced to one-fifth, then the force between them is: [RRB ALP Tier - I (30/08/2018) Morning]

Correct Answer: (d) 25 F
Solution:

30. An electric lamp of 100 W is used for 5 hours per day. How much energy will be consumed by the lamp in 3 days? [RRB ALP Tier - I (30/08/2018) Afternoon]

Correct Answer: (a) 1.5 units
Solution:

Power of lamp = 100w = 100/1000 = 0.1Kw,
time = 5 hrs × 3 days = 15 hrs.
Consumed electrical energy = power × time, E = 0.1kw × 15h = 1.5 kw-h = 1.5 units.
Therefore, the electric lamp will consume 1.5 kilowatt-hours of energy in 3 days.