Physics · NDA previous year questions

Evaporation from the surface of a given liquid takes place more rapidly when

1. A.the temperature is high and the surface area of the liquid is large
2. B.the temperature is low and the surface area of the liquid is large
3. C.the temperature is low and the surface area of the liquid is small
4. D.the temperature is high and the surface area of the liquid is small

Which of the following statements correctly explains/explain the existence of a positive force between two electric charges? 1. Both the charges are positive. 2. Both the charges are negative. 3. Both the charges are oppositely charged. Select the correct answer using the code given below.

1. A.1 only
2. B.2 only
3. C.1 and 2 only
4. D.1, 2 and 3

An electric wire of resistance 50 ohm is cut into five equal wires. These wires are then connected in parallel. What is the equivalent resistance of this combination?

1. A.2 ohm
2. B.10 ohm
3. C.0.5 ohm
4. D.5 ohm

The electric field lines from an isolated positively charged conducting sphere are

1. A.tangential to the conducting surface
2. B.at right angles to the conducting surface and towards the centre of the sphere
3. C.at any angle to the conducting surface
4. D.at right angles to the conducting surface and outwards from the centre of the sphere

The frequency of an alternating current is 3 Hz. It implies that

1. A.there are 6 cycles/s
2. B.there are 3 cycles/s
3. C.there are 2 cycles/s
4. D.there is only 1 cycle/s

Which one of the following correctly represents the SI unit of resistivity?

1. A.Ω
2. B.Ω / m
3. C.Ω cm
4. D.Ω m

What is the current required to light a 60 W incandescent bulb in a domestic supply of 240 V ?

1. A.0.5 A
2. B.0.25 A
3. C.1.0 A
4. D.5.0 A

The magnetic field produced by a current-carrying straight wire at a point outside the wire depends

1. A.inversely on the distance from it
2. B.directly on the distance from it
3. C.inversely at short distances and directly at large distances from it
4. D.directly on the distance (at short distances) and inversely on the distance (at long distances) from it

What is the dimension of gravitational constant?

1. A.$\mathrm{M}{\mathrm{L}}^3{\mathrm{T}}^{-2}$
2. B.${\mathrm{M}}^{-1}{\mathrm{L}}^3{\mathrm{T}}^{-2}$
3. C.${\mathrm{M}}^2{\mathrm{L}}^{-2}{\mathrm{T}}^{-2}$
4. D.${\mathrm{M}}^2{\mathrm{L}}^{-1}{\mathrm{T}}^{-2}$

A ball is thrown vertically upward with a speed of 40 m/s. The time taken by the ball to reach the maximum height would be approximately

1. A.2 s
2. B.3 s
3. C.4 s
4. D.5 s

All objects experience a buoyancy when they are immersed in a fluid. Buoyancy is

1. A.a downward force
2. B.a downward pressure
3. C.an upward force
4. D.an upward pressure

According to Fleming's right-hand rule, if the forefinger indicates the direction of the magnetic field and the thumb shows the direction of motion of the conductor, then the stretched middle finger will predict the direction of

1. A.force acting on the conductor
2. B.electric field
3. C.induced current
4. D.current

Two resistors ${\mathrm{R}}_1$ and ${\mathrm{R}}_2$ arranged in parallel combination in an electrical closed circuit are made of the same material and of the same thickness. If the length of ${\mathrm{R}}_2$ is twice the length of ${\mathrm{R}}_1$, then the total resistance R satisfies

1. A.$3\mathrm{R}=2{\mathrm{R}}_1$
2. B.$3\mathrm{R}=2{\mathrm{R}}_2$
3. C.$2\mathrm{R}=3{\mathrm{R}}_1$
4. D.$2\mathrm{R}=3{\mathrm{R}}_2$

What is the magnification produced by a concave lens of focal length 10 cm, when an image is formed at a distance of 5 cm from the lens?

1. A.2.0
2. B.1.0
3. C.0.5
4. D.0.33

A wooden box of mass 2 kg and dimensions (30 cm × 15 cm × 10 cm) is placed on a table with sides 30 cm and 10 cm touching the tabletop. Which one of the following is the approximate pressure exerted on the table?

1. A.$111.1N/{\mathrm{m}}^2$
2. B.$222.2N/{\mathrm{m}}^2$
3. C.$333.3N/{\mathrm{m}}^2$
4. D.$666.6N/{\mathrm{m}}^2$

Buoyancy is a/an

1. A.Upward pressure
2. B.Downward pressure
3. C.Downward force
4. D.Upward force

Weight and mass of an object are defined with Newton’s laws of motion. Which among the following is true ?

1. A.Weight is a constant of proportionality.
2. B.Mass is a constant of proportionality.
3. C.Mass is not a constant of proportionality.
4. D.Weight is a universal constant.

Fundamental laws of physics require

1. A.conservation of energy and non-conservation of charge.
2. B.conservation of charge and non-conservation of linear momentum.
3. C.conservation of charge and non-conservation of energy.
4. D.conservation of energy, momentum and charge.

Work is said to be one Joule when a force of

1. A.4 N moves an object by 25 cm.
2. B.2 N moves an object by 1 m.
3. C.1 N moves an object by 1 cm.
4. D.1 N moves an object by 50 cm.

A uniform motion of a car along a circular path experiences

1. A.a change in speed due to a change in its direction of motion.
2. B.a change in velocity due to a change in its direction of motion.
3. C.a change in momentum due to no change in its direction of motion.
4. D.a constant momentum due to a change in its direction of motion.

Three equal resistors are connected in parallel configuration in a closed electrical circuit. Then the total resistance in the circuit becomes

1. A.one-third of the individual resistance.
2. B.two-third of the individual resistance.
3. C.equal to the individual resistance.
4. D.three times of the individual resistance.

Imagine a current-carrying straight conductor with magnetic field of lines in anti-clockwise direction. Then the direction of current is determined by

1. A.the Right-Hand Thumb rule and it would be in the downward direction.
2. B.the Left-Hand Thumb rule and it would be in the downward direction.
3. C.the Right-Hand Thumb rule and it would be in the upward direction.
4. D.the Left-Hand Thumb rule and it would be in the upward direction.

Tyndall effect is a phenomenon of

1. A.scattering of light by the colloidal particles.
2. B.refraction of light by the colloidal particles.
3. C.dispersion of light by dust particles.
4. D.refraction of light by dust particles.

Power of a lens of focal length 25 cm is

1. A.+2.5 Diopter
2. B.+3 Diopter
3. C.+4 Diopter
4. D.+5 Diopter

Spherical mirror formula relating an object distance ‘u’, image distance ‘v’ and focal length of mirror ‘f’ may be applied to a plane mirror when

1. A.focal length goes to infinity.
2. B.focal length goes to zero.
3. C.image distance goes to zero.
4. D.image distance goes to infinity.