Test : Physics - 1


20 Questions MCQ Test NDA (National Defence Academy) Mock Test Series | Test : Physics - 1


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This mock test of Test : Physics - 1 for Defence helps you for every Defence entrance exam. This contains 20 Multiple Choice Questions for Defence Test : Physics - 1 (mcq) to study with solutions a complete question bank. The solved questions answers in this Test : Physics - 1 quiz give you a good mix of easy questions and tough questions. Defence students definitely take this Test : Physics - 1 exercise for a better result in the exam. You can find other Test : Physics - 1 extra questions, long questions & short questions for Defence on EduRev as well by searching above.
QUESTION: 1

The escape velocity for a body of mass 1 kg from the Earth surface is 11.2 kms-1. The escape velocity for a body of mass 100 kg would be

Solution:

Escape velocity is independent of mass of the object. It depends only on the mass of the planet as.

QUESTION: 2

If the temperature inside a room is increased, the relative humidity will  

Solution:

If the water vapor content stays the same and the temperature drops, the relative humidity increases. If the water vapor content stays the same and the temperature rises, the relative humidity decreases. This is because colder air doesn't require as much moisture to become saturated as warmer air.

QUESTION: 3

A cell has an emf 1.5 V. When connected across an external resistance of 2 Ω, the terminal potential difference falls to 1.0 V. The internal resistance of the cell is 

Solution:

QUESTION: 4

The specific resistance of a conductor increases with 

Solution:

The specific resistance (resistivity) of a metallic conductor nearly increases with increasing temperature as shown in figure. This is because, with the increase in temperature the ions of the conductors vibrate with greater amplitude and the collisions between electrons and ions become more frequent, over a small temperature range (up to 100°C). The resistivity of a metal can be represented approximately by the question

The factor a is called with temperature coefficient of resistivity. 
 

QUESTION: 5

There is the following relation between the velocity (v) and time (t) of a particle:

v = 20 + 0.1 t² The particle is—

Solution:

Therefore, acceleration is not constant but time dependent.

QUESTION: 6

In a period, the elements are arranged in the order of- 

Solution:

The first ionization energy generally increases ongoing across a period. This is because on crossing a period, more protons are being added to the nuclei of the atoms. This results in an increase in nuclear charge. The electrons in the outer energy levels will be more tightly held, and more difficult to remove.

QUESTION: 7

Transition metals are often paramagnetic owing to- 

Solution:

Transition elements containing one or more unpaired electrons show paramagnetic behavior where the effects of individual electrons are not mutually compensated. The magnetic moment due to unpaired electron spins is aligned parallel to the external magnetic field more effectively.

QUESTION: 8

 With rise of boiling point of water the latent heat of steam 

Solution:

As the external pressure increases the boiling point increases. Latent heat of vaporization means the energy required to overcome the intermolecular interactions for increasing the volume when a liquid boils, so latent heat of vaporization decreases as the boiling point increase

QUESTION: 9

 Velocity of light is Maximum in 

Solution:

A vacuum is completely empty. Light traveling through a vacuum will encounter nothing of which is scattered so it can obtain its maximum speed.

QUESTION: 10

When a ray of light enters a glass slab from air 

Solution:

When a ray of light enters a glass slab from the air, the velocity and wavelength decrease. V=nℷ , Where velocity and wavelength are directly proportional.

QUESTION: 11

The plot given below represent displacement S of a  particle with time-t. The particle is

Solution:

If the body is moving with uniform acceleration in the displacement-time graph, the body covering an unequal distance in equal interval of time and the speed is increasing and the slope is positive.

QUESTION: 12

A body moves with a constant speed in a circle-

Solution:

Work is only said to be done when there is displacement. The work done on a body moving in a circular path is also zero. This is because, when a body moves in a circular path, then the centripetal force acts along the radius of the circle, and it is at right angles to the motion of the body.

QUESTION: 13

When light passes from one medium to another, the physical quantity that remains unchanged is 

Solution:

when light travels from one medium to another only speed of the light and wavelength changed and frequency does NOT change, it remains constant in all medium. The speed of light and wavelength changes in order to maintain the constant frequency.

QUESTION: 14

The circular motion of a particle with constant speed is 

Solution:

In a circular motion, particle repeats its motion after equal intervals of time. So, a particle moving on a circular path is periodic but not simple harmonic as it does not execute to and fro motion about a fixed point.

QUESTION: 15

For which of the following substances, the resistance decreases with increases in temperature?

Solution:

Resistance of a semiconductor decreases with the increasing temperature. Pure silicon is a semiconductor.

QUESTION: 16

A particle has initial velocity (3i ̂+4j ̂) and has acceleration (0.4i ̂+0.3j ̂ ). Its speed after 10 s is

Solution:

Given, initial velocity (u) = 3i ̂+4j ̂

Final velocity (v) =? 

Acceleration (a) = (0.4i ̂+0.3j ̂)

Time (t) = 10 s 

From first equation of motion, v = u + at 

v = 3i ̂+4j ̂+10(0.4i ̂+0.3j ̂) 

 

v = 7i ̂+7j ̂⇒|v|=7√2

QUESTION: 17

The potential energy of a system increases, if work is done

Solution:

The potential energy of a system increases, if work is done by the system against a conservative force.

QUESTION: 18

 When a mass is rotating in a plane about a fixed point, its angular momentum is directed along

Solution:

As we know that

Angular momentum L = m (r x v)

So, here angular momentum is directed along a line perpendicular to the plane of rotation.

QUESTION: 19

A solid sphere of radius R is placed on a smooth horizontal surface. A horizontal force F is applied at height h from the lowest point. For the maximum acceleration of the Centre of mass

Solution:

The linear acceleration of Centre of mass will be a =F/m, wherever the force is applied. Hence, the acceleration will be same whatever the value of h may be.

QUESTION: 20

The wettability of a surface by a liquid depends primarily on

Solution:

The wettability of a surface by a liquid depends primarily on angle of contact between the surface and the liquid.

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