# ICSE Class 10th Physics 8 – Spectrum MCQs

#### Work done by the gravitational force on a body is ____.

Correct! Wrong!

When a body is carried along the direction of the gravitational force, the work done is positive and vice-versa. When the displacement is made perpendicular to the direction of the gravitational force, the work done is zero.

#### Clouds look white because, light of all wavelengths enter our eyes due to scattering.

Correct! Wrong!

The concentration and the size of water droplets is large in clouds, the intensity of scattering by large particles is independent of wavelength. Thus, light of all wavelengths enter our eyes and the clouds appear white.

#### When the force applied and the displacement of the body is inclined at 90°, with each other, the work done is ____.

Correct! Wrong!

Work done = FScosθ As, cos90° = 0 Therefore, work done is zero.

#### The amount of light scattered, by air molecules increases with increase in wave length.

Correct! Wrong!

The amount of light scattered, by air molecules increases with decrease in wavelength of light. Thus, blue light is scattered more than red light.

#### The angle between the two refracting faces is known as the angle of deviation.

Correct! Wrong!

The angle between the two refracting faces is called the angle of prism or the refracting angle.

#### Twinkling of stars, apparent sunrise and sunset can be explained by the phenomenon of ____.

Correct! Wrong!

Twinkling of stars, apparent sunrise and sunset can be explained by the phenomenon of atmospheric refraction.

#### A transparent medium bounded by two plane surfaces inclined at an angle is known as a ____.

Correct! Wrong!

A transparent medium bounded by two plane surfaces inclined at an angle is known as a prism.

#### The angle 'δ' through which incident ray has been deviated by the prism is known as ____.

Correct! Wrong!

The angle 'δ' through which incident ray has been deviated by the prism is known as angle of deviation.

#### Which of the following is responsible for the formation of a rainbow?

Correct! Wrong!

Refraction, internal reflection and dispersion are responsible for the formation of a rainbow. During the formation of a rainbow, sunrays incident on the water droplets, first refract with dispersion, then undergo internal reflection and then refract again at the other surface of the drop with further dispersion. Thus, light undergoes refraction two times, internal reflection one time, and dispersion in the course of refraction. This is the reason that we are able to view the rainbow, even though we stand in between the source of light (the sun) and the dispersing medium (the rain drops). The rainbow that we observe is hence, called the secondary rainbow.

#### An isosceles glass prism having one angle 90° is called ____prism.

Correct! Wrong!

An isosceles glass prism having one angle 90° is called totally reflecting prism because, it turns the ray by 90° due to total internal reflection.

#### The frequency of ____ colour of light is maximum and ____ colour of light is minimum.

Correct! Wrong!

The frequency of violet colour of light is maximum and red colour is minimum.

#### The phenomenon of splitting of white light into its constituent colours, on passing through a prism is called ____.

Correct! Wrong!

The phenomenon of splitting of white light into its constituent colours, on passing through a prism is called dispersion.

#### The ____ component of sunlight is least scattered during sunrise and sunset.

Correct! Wrong!

Violet, blue, green component of sunlight which are of shorter wave length are scattered away during sunrise and sunset. Red colour is least scattered, hence, the Sun appears red during sunrise and sunset.

#### Work is measured as a product of ____.

Correct! Wrong!

Work done is given by the product of force and displacement, represented by, Work = force × displacement.

#### A body is moved from A to B in three different paths in conservative force field. The work done will be maximum when the body is moved along the longest path.

Correct! Wrong!

Work done by the conservative force does not depend upon the path followed by the body. It depends upon the displacement covered from initial position to final position.

#### The band of colours obtained by dispersion of light is called ____ of light.

Correct! Wrong!

The band of colours obtained by dispersion of light is called spectrum of light.

#### Formation of a rainbow does not depend on ____.

Correct! Wrong!

Formation of a rainbow depends on dispersion, total internal reflection and refraction but not on interference.

#### Stars would appear to twinkle if we view them from moon.

Correct! Wrong!

Moon does not have atmosphere. So, stars would not appear to twinkle if viewed them from moon, since there is no atmospheric refraction.

#### According to Rayleigh the phenomenon of absorption of light and then re-radiating it by the molecules of atmosphere in different directions is called ____ of light.

Correct! Wrong!

According to Rayleigh the phenomenon of absorption of light and then re-radiating it by the molecules of atmosphere in different directions is called scattering of light.

#### The scattering of light by particles in its path is called ____.

Correct! Wrong!

Light is scattered when it falls on various types of suspended particles in its path, which is discovered by Tyndall and known as Tyndall effect.

#### Blue coloured light present in sunlight, is scattered ____ times more than the red light.

Correct! Wrong!

Blue light has shorter wavelength, so it is scattered 10 times more than the red light.

#### The unit Nm is equivalent to ____.

Correct! Wrong!

Unit Nm is equivalent to J.

#### We can see the Sun before the actual sunrise by about ____ minutes.

Correct! Wrong!

We can see the Sun before the actual sunrise by about 2 minutes.

#### The colour of the light that is scattered most does not depend on the size of the scattering particles.

Correct! Wrong!

The colour of the light that is scattered most depends on the size of the scattering particles. Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths.

#### A ray of light bends more when it enters into a medium. The refractive index of that medium is low.

Correct! Wrong!

According to Snell's law, refractive index is inversely proportional to the sine of angle of refraction. When light ray bends more, the angle of refraction is small. Hence, the refractive index of that medium is high.

ICSE Class 10th Physics 8 - Spectrum MCQs
Poor

Average

Good

Excellent