Physics (CDS-Solved Paper)

Total Questions: 50

31. The pressure of a fluid varies with depth h as p = pₒ , ρgh where p is the fluid density. This expression is associated with [Morning Shift-2018 (I)]

Correct Answer: (a) Pascal’s law
Solution:

32. Why is argon gas used along with tungsten wire in an electric bulb? [Morning Shift-2018 (I)]

Correct Answer: (a) To increase the life of the bulb
Solution:

Argon being an inert gas used in electric bulb to increase the life of the bulb. It prevents the tungsten filaments from descend too quickly.

33. Which one of the following is the correct relation between the Kelvin temperature T and the Celsius temperature tᶜ ? ? [Morning Shift-2018 (I)]

Correct Answer: (d) T = tᶜ + 273.15
Solution:

To change a temperature from Kelvin scale to the Celsius scale, you have to subtract 273.15 from the given temperature and to convert a temperature from Celsius scale to the Kelvin scale, you have to add 273.15 to the given temperature. Hence, the correct relation is T = tᶜ + 273.15

34. Sound waves cannot travel through a [Morning Shift-2018 (I)]

Correct Answer: (d) wooden hollow pipe placed in vacuum
Solution:

Sound waves cannot travel in vacuum, it need a material medium to propagate. Hence,it cannot passes through the wooden hollow pipe placed in vacuum.

35. Which one of the following is the value of 1 nanometre? [Morning Shift-2018 (I)]

Correct Answer: (a) 10⁻⁷ cm
Solution:

1 nanometre = 10⁻⁹ metre
= 1 × 10⁻⁷ centimeter.
Its unit of length.

36. Consider the following statements. [Morning Shift-2018 (I)]

1. There is no net moment on a body which is in equilibrium.
2. The momentum of a body is always conserved.
3. The kinetic energy of an object is always conserved.
Which of the statement(s) given above is/are correct?

Correct Answer: (c) 1 and 2
Solution:

Kinetic energy is the energy possessed by an object due to its motion. The kinetic energy of an object increases with its speed. The only kinetic energy of an object cannot be conserved but the sum of kinetic and potential energies is conserved. The momentum of a body is always conserved due to conservation of momentum. When a body is in equilibrium, there is no net moment present in it. Hence, option (c) is correct.

37. Working of safety fuses depends upon [Morning Shift-2018 (I)]

Correct Answer: (c) 3 and 4
Solution:

Working of safety fuses depends upon magnitude of the current and heating effect of the current. Hence, option (c) is correct.

38. An electron and a proton starting from rest are accelerated through a potential difference of 1000 V. Which one of the following statements in this regard is correct? [Evening Shift-2017 (II)]

Correct Answer: (b) The speed of the electron will be higher than that of the proton.
Solution:

39. Two wires are made having same length l and area of cross-section A. Wire 1 is made of copper and wire 2 is made of aluminium. It is given that the electrical conductivity of copper is more than that of aluminium. In this context, which one of the following statements is correct? [Evening Shift-2017 (II)]

Correct Answer: (b) The resistance of wire 2 will be higher than that of wire 1.
Solution:


40. A ray of light is incident on a plane mirror at an angle of 40° with respect to surface normal. When it gets reflected from the mirror, it undergoes a deviation of [Evening Shift-2017 (II)]

Correct Answer: (b) 100°
Solution:

A ray of light is incident on a plane mirror as shown in figure.