Practice MCQ Questions and answers on Physics-GK

61

What is refractive index ?

A) It is defined as the ratio of speed of light in the medium to the speed of light in vacuum. B) It is defined as the product of speed of light in medium and in vacuum. C) It is defined as the ratio of speed of light in vacuum to the speed of light in the medium. D) None of above

Discuss

Answer & Solution

Answer: Option C

Solution:

The ratio of the velocity of light in a vacuum to its velocity in a specified medium.

62

A star appears twinkling in the sky because of

A) Scattering of light by atmosphere B) Reflection of light by atmosphere C) Refraction of light by atmosphere D) Diffraction of light by atmosphere

Discuss

Answer & Solution

Answer: Option C

Solution:

A star appears twinkling in the sky because of refraction of light by atmosphere.

63

What type of lens is used in a magnifying glass

A) Concave B) Plano-concave C) Convex D) None of the above

Discuss

Answer & Solution

Answer: Option C

Solution:

Convex lens is used in magnifying glass.

64

Time of exposure required for taking photograph of an object depends upon the

A) Brightness of the object B) Skill of photographer C) Proximity of object D) Size of the object

Discuss

Answer & Solution

Answer: Option A

Solution:

The total exposure is proportional to this exposure time, or duration of light reaching the film or image sensor. The correct exposure for a particular object depends on the brightness of the object to be photographed.

65

A concave lens always forms

A) A real image B) A virtual image C) An image type which depends on object characteristics D) An image type which depends on lens curvature

Discuss

Answer & Solution

Answer: Option B

Solution:

A concave lens always forms a virtual image.

66

A concave lens always forms an image which is

A) Real and erect B) Virtual and erect C) Real and inverted D) Virtual and inverted

Discuss

Answer & Solution

Answer: Option B

Solution:

A concave lens always forms an image which is virtual and erect.

67

Which one of the following determines the sharpness of image in a camera ?

A) The aperture B) The exposure time C) The focal length of the lens D) Size of the camera

Discuss

Answer & Solution

Answer: Option A

Solution:

Image quality is a characteristic of an image that measures the perceived image degradation (typically, compared to an ideal or perfect image). Imaging systems may introduce some amounts of distortion or artifacts in the signal, so the quality assessment is an important problem. Sharpness determines the amount of detail an image can convey. System sharpness is affected by the lens (design and manufacturing quality, focal length, aperture, and distance from the image center) and sensor (pixel count and anti-aliasing filter).

68

Dioptre is the unit of

A) Power of a lens B) Focal length of a lens C) Light intensity D) Sound intensity

Discuss

Answer & Solution

Answer: Option A

Solution:

Dioptere is the unit of power of a lens.

69

The part of the eye having the largest refractive index is :

A) Cornea B) Aqueous humor C) Lens D) Vitreous humor

Discuss

Answer & Solution

Answer: Option C

Solution:

The part of the eye having the largest refractive index is lens.

70

Vehicles use ________ to see the objects coming from behind.

A) Concave lens B) Convex lens C) Convex mirror D) Concave mirror

Discuss

Answer & Solution

Answer: Option C

Solution:

Convex mirror is used as a rear view mirror in the vehicles because convex mirror always forms virtual, erect and diminished images irrespective of distance of the object. A convex mirror enables a driver to view large area of the traffic behind him.