[MCQ]Physics MCQs For UPSC(NDA/NA) Exam, SET 8||DEB STUDY

PHYSICS OBJECTIVE Q&A FOR UPSC (NDA/NA) EXAM

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UPSC NDA/NA PHYSICS MCQ Q.1

A pendulum beats faster than a standard pendulum. In order to bring it to the standard beat, the length of the pendulum is to be

(a) reduced

(b) increased

(c) reduced and the mass of the bob increased

(d) reduced and also the mass of the bob reduced

Ans.(a)

UPSC NDA/NA PHYSICS MCQ Q.2

The ratio of the focal length of the objective to the focal length of the eyepiece is greater than one for

(a) a microscope

(b) a telescope

(c) both microscope and telescope

(d) neither microscope nor telescope

Ans.(a)

         ((Microscope: a microscope is an optical instrument to see small objects as magnified one. It consists of a convex lens of small focal length.

           Telescope: Telescope is an optical instrument to clearly observe the distant objects. It consists of two convex lens, an objective lens of larger focal length and an eyepiece of small focal length.))  

UPSC NDA/NA PHYSICS MCQ Q.3

The effective resistance of three equal resistances, each of resistance r , connected in parallel, is

(a) 3/r

(b) r/3

(c) 3r 

(d) r^3  

Ans.(b)

UPSC NDA/NA PHYSICS MCQ Q.4

A fan produces a feeling of comfort during hot weather, because

(a) our body radiates more heat in air 

(b) fan supplies cool air

(c) conductivity of air increases

(d) our perspiration evaporates rapidly

Ans.(a)

            ((Explanation :: a fan produces a feeling of comfort during hot weather because the respiration from our body evaporates rapidly due to air from the fan and evaporation results in the cooling of liquids))

UPSC NDA/NA PHYSICS MCQ Q.5

If an object is placed at the centre of curvature of a concave mirror, the position of the image is

(a) at the principal focus

(b) between the principal focus and the centre of curvature

(c) at the centre of curvature

(d) beyond the centre of curvature

Ans.(c)

UPSC NDA/NA PHYSICS MCQ Q.6

The ratio of velocity of X-rays to that of gamma rays

(a) is <1

(b) is >1

(c) is 1

(d) depends upon the ratio of their frequencies

Ans.(c)

           ((Explanation :: the X-rays and gamma rays are electromagnetic waves. The velocity of electromagnetic wave in vacuum is equal to the velocity of light . Hence, electromagnetic wave moves with speed of light in vacuum,

          therefore, the ratio of velocity of X-rays and gamma rays is equal to 1.))

UPSC NDA/NA PHYSICS MCQ Q.7

Which one of the following pairs of rays is electromagnetic in nature

(a) Beta rays and gamma rays

(b) Cathode rays and X-rays

(c) Alpha rays and beta rays

(d) X-rays and gamma rays

Ans.(d)

UPSC NDA/NA PHYSICS MCQ Q.8

The magnetic lines of force due to the bar magnet

(a) intersect inside the body of the magnet 

(b) intersect at neutral points only 

(c) intersect only at north and south poles

(d) cannot intersect at all

Ans.(d)

UPSC NDA/NA PHYSICS MCQ Q.9

The specific resistance of a conducting wire depends upon 

(a) length of the wire, area of cross-section of the wire and material of the wire

(b) length of the wire and area of cross-section of the wire but not on the material of the wire

(c) material of the wire only but neither on the length of the wire nor on the area of cross-section of the wire

(d) length of the wire only.

Ans.(c)

          ((Explanation :: Specific resistance or resistivity is property of material and does not depend upon its shape and size, its length, thickness and area of cross-section.))

UPSC NDA/NA PHYSICS MCQ Q.10

When X-rays are produced

(a) heat is generated at the target

(b) heat is absorbed at the target

(c) the temperature of the target remains constant

(d) brilliant light is seen at the target

Ans.(a)

             ((Explanation :: When X-rays are produced, a stream of highly energetic electrons are focussed at the target (made of tungsten or molybdenum ).When these energetic electrons fall on the target , most of the energy of these electrons is converted into heat energy and heat is generated at the target.))

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