STD-X, HUMAN EYE AND THE COLOURFUL WORLD: Dispersion, MOST IMPORTANT MCQs

1. Which of the following statements is correct regarding the propagation of light of different colours of white light in air?
(a) Red light moves fastest.
(b) Blue light moves faster than green light.
(c) All the colours of the white light move with the same speed.
(d) Yellow light moves with the mean speed as that of the red and the violet light

ANS: All the colours of the white light move with the same speed

 

2.  The splitting of light into its component colours is called-
(a) Spectrum
(b) Dispersion
(c) Tyndall effect
(d) Refraction

 

ANS: Dispersion

 

3.  Dispersion is caused due to _____ of light.

(a) reflection

(b) refraction

(c) scattering

(d) reflection and refraction

 

ANS: refraction

 

4.  The dispersive power of prism depends upon-
(a) The shape of the prism
(b) The material of the prism
(c) The angle of the prism
(d) Height of the prism

 

ANS: the material of the prism

 

5.  The dispersive power will be maximum for-
(a) Flint glass (n=1.65)
(b) Crown glass (n=1.51)
(c) Mixture of glass
(d) None of these

 

ANS: Flint glass

 6.  Sumitra was given two glass prisms. One was made of ordinary glass and other one was of flint glass (Given that refractive index of flint glass is more than that of ordinary glass). She traced the path of rays through both and after observing the diagram and concluded that bending of light for given angle of incidence was

(a) more in the prism made of flint glass

(b) more in the prism made of ordinary glass

(c) same in both the glass prisms

(d) independent of the nature of glass of which the prism was made

 

ANS: more in the prism made of flint glass

6.  Sumitra was given two glass prisms. One was made of ordinary glass and other one was of flint glass (Given that refractive index of flint glass is more than that of ordinary glass). She traced the path of rays through both and after observing the diagram and concluded that bending of light for given angle of incidence was

(a) more in the prism made of flint glass

(b) more in the prism made of ordinary glass

(c) same in both the glass prisms

(d) independent of the nature of glass of which the prism was made

 

ANS: more in the prism made of flint glass

 

7.  For a light travelling in a prism choose the correct option. Inside the prism,

(a) all the colours have same angle of refraction

(b) the colour with more deviation has lesser refractive index

(c) the colour with lesser deviation has more speed

(d) all the colours travel with same speed

 

ANS: the colour with lesser deviation has more speed

 

8.  Which of the colours of visible light has maximum wavelength?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Red

 

9.  Which of the colours of visible light has minimum frequency?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Red

 

10.  Which colour has maximum speed in glass?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Red

 

11.  Which ray is least deviated by a prism?
(a) Violet ray
(b) Green ray
(c) Red ray
(d) Yellow ray

 

ANS: Red ray

 

12.  For which colour, refractive index of glass is minimum?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Red

 

13.  When white light enters a glass prism from air, the angle of deviation is least for
(a) blue light
(b) yellow light
(c) violet light
(d) red light

 

ANS: red light

 

14.  Which of the colours of visible light has minimum wavelength?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Violet

 

15.  Which of the colours of visible light has maximum frequency?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Violet

 

16.  Which colour has minimum speed in glass?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Violet

 

17.  Which ray is more deviated by a prism?
(a) Violet ray
(b) Green ray
(c) Red ray
(d) Yellow ray

 

ANS: Violet ray

 

18.  When white light enters a glass prism from air, the angle of deviation is maximum for
(a) blue light
(b) yellow light
(c) red light
(d) violet light

 

ANS: Violet light

 

19.  For which colour, refractive index of glass is maximum?
(a) Yellow
(b) Red

(c) Violet

(d) Green

 

ANS: Violet

 

20.  When white light enters a prism, it gets split into its constituent colours. This is due to

(a) different refractive index for different wavelength of each colour

(b) each colour has the same velocity in the prism.

(c) prism material has high density.

(d) Scattering of light 

 

ANS: different refractive index for different wavelength of each colour

 

21.  What is the relation between angle of deviation of a coloured light to its refractive index in the given transparent medium?

(a) lesser the angle of deviation, lesser is its refractive index

(b) higher the angle of deviation, lesser is its refractive index

(c) angle of deviation = C x refractive index

(d) angle of deviation x refractive index = C

 

ANS: lesser the angle of deviation, lesser is its refractive index

 

22.  Which of the following is the correct order of angle of deviation?

(a) Red > Green > Blue

(b) Blue > Yellow > Orange

(c) Orange > Red > Green

(d) Blue > Green > Violet

 

ANS: Blue > Yellow > Orange

 

23.  Which of the following is the correct order of wavelength?

(a) Red > Green > Yellow

(b) Red > Violet > Green

(c) Yellow > Green > Violet

(d) Red > Yellow > Orange

 

ANS: Yellow > Green > Violet

 

24.  Which of the following is the correct order of speed of light in glass?

(a) Red > Green > Blue

(b) Blue > Green > Red

(c) Violet > Red > Green

(d) Green > Red > Blue

 

ANS: Red > Green > Blue

 

25.  Which of the following options is Correct?

(a) n_violet > n_red

(b) n­_red > n_violet

(c) n_orange > n_indigo

(d) n_orange = n_indigo

 

ANS: n_violet > n_red

 

26.  Which of the following options is correct?

(a) V_green < V_yellow

(b) V_green > V_yellow

(c) V_indigo > V_blue

(d) V_indigo = V_green

 

ANS: V_green < V_yellow

 

27.  Light of two colours A and B passes through a prism. Colour A deviates more than B from its path of incidence. Choose the correct option. 

(a) A has higher speed than B

(b) A has lesser speed than B

(c) A and B have same speed in prism only

(d) A and B have same speed in air and prism

 

ANS: A has lesser speed than B

 

28.  Name the scientist who was the first to use a glass prism to obtain the spectrum of sunlight.
(a) Isaac Newton
(b) Einstein
(c) Kepler
(d) Hans Christian Oersted 

ANS: Isaac Newton

 

29.  When a white light passes through a hollow prism, then there is

(a) dispersion as usual

(b) only red light as emergent light

(c) only blue light as emergent light

(d) no dispersion

 

ANS: no dispersion

 

30.  When two prisms are placed parallel with each other but second prism is placed inverted with respect to the first then,

(a) dispersed light is twice brighter

(b) dispersed light is half brighter

(c) no dispersion is observed

(d) spectrum of more than seven colours is seen

 

ANS: no dispersion is observed

 

31.  The image shows the dispersion of the white light in the prism.

                

What will be the colours of the X, Y and Z?

(a) X: red; Y: green; Z: violet

(b) X: violet; Y: green; Z: red

(c) X: green; Y: violet; Z: red

(d) X: red; Y: violet; Z: green

 

ANS: X: Violet, Y: Green, Z: Red

 

32.  A prism ABC (with BC as base) is placed in different orientations. A narrow beam of white light is incident on the prism as shown in the Figures given below. In which of the following cases, after dispersion, the third colour from the top corresponds to the colour of the sky?

ANS: ii

 

33.  Which of the following is a natural phenomenon which is caused by the dispersion of sunlight in the sky?
(a) Twinkling of stars
(b) Stars seem higher than they actually are
(c) Advanced sunrise and delayed sunset
(d) Rainbow

 

ANS: Rainbow

 

34.  Which of the following phenomena of light are involved in the formation of a rainbow?
(a) Reflection, refraction and dispersion
(b) Refraction, dispersion and total internal reflection
(c) Refraction, dispersion and internal reflection
(d) Dispersion, scattering and total internal reflection

ANS: Refraction, Dispersion and internal reflection

 

35.  In the formation of rainbow, the sunlight rays emerge from rain-drop after,

(a) one internal reflection, one dispersion and one refraction

(b) one internal reflection, one dispersion and two refractions

(c) two internal reflections, one dispersion and one refraction

(d) two internal reflections, one dispersion and two refractions

 

ANS: one internal reflection, one dispersion and two refractions.

 

36. The rainbow can be seen on sunny day when observer looks at the sky through water fountain and -

(a) the Sun and observer are co-axial with Sun in front of the observer

(b) the observer and clouds are co-axial

(c) the Sun and observer are co-axial with the Sun behind the observer

(d) the Sun and clouds are co-axial

ANS: the Sun and observer are co-axial with Sun behind the observer