# WBBSE Class 10 Physical Science MCQ Questions Chapter 5 Light

Well structured WBBSE Class 10 Physical Science MCQ Questions Chapter 5 Light can serve as a valuable review tool before exams.

## Light Class 10 WBBSE MCQ Questions

Multiple Choice Questions (MCQ) :

Question 1
The formation of spectrum is due to:
(A) reflection
(B) refraction
(C) dispersion of light
(C) dispersion

Question 2.
The terminal colours of pure spectrum of white light are:
(A) Blue and violet
(B) Red and orange
(C) Red and violet
(C) Red and violet

Question 3.
Yellow colour is called:
(A) primary
(B) secondary
(C) middle colour.
(B) secondary colour

Question 4.
The (A) seven (B) six (C) eight colours can be seen distinctly in pure spectrum.
(A) seven

Question 5.
The dispersion of white light was first observed by :
(A) Sir Issac Newton
(B) Boyle
(C) Max well
(A) Sir Issac Newton

Question 6.
The would be towards the base of the prism.
(A) violet
(B) green
(C) orange
(A) violet

Question 7.
The arrangement of seven colours of spectrum is:
(A) VIBGYOR
(B) VBIGOYR
(C) RAINBOW
(A) VIBGYOR

Question 8.
Linear magnification is equal to:
A (length of image) / (length of the object)
(B) (length of image) × (length of the object)
C) (length of image) + (length of the object)
(D) (length of image) – (length of the object)
(B) (length of image) × (length of the object)

Question 9.
The object is placed in between ‘f’ and ‘2f’ in convex lens, the size of image will be
(A) greater in size the object
(B) smaller in size than the object
(C) equal in size of the object.
(A) greater in size than the object.

Question 10.
To form virtual image on the same side of the object in case of convex lens, object should be placed:
(A) in between the lens and the focus
(B) in between ‘f’ and ‘2f’
C) at ‘2f’ from the lens
(D) at a distance greater than ‘2f’ from the lens.
(A) in beiveen the lens and the focus

Question 11.
To form the image of real, inverted and equal to the size of the object, the object should be placed:
(A) in between the lens and the focus
(B) at a distnace greater then ‘2f’ from the lens
(C) at ‘2f’ from the lens
(D) in between ‘f’ and ‘2f’
(C) at ‘2f’ from the lens

Question 12.
A plane mirror produces a magnification of :
(A) -1
(B) +1
(C) Zero
(D) between O and + α
(B) +1

Question 13.
When a mirror is rotated through an angle θ, the reflected ray from it turns through an angle of
(A) θ
(B) $$\frac{\theta}{2}$$
(C) 2 θ
(D) 0
(C) 2 θ

Question 14.
An object is placed at a distance of 40 cm in front of a concave mirror of focal length 20 cm. The image produced is
(A) virtual and inverted
(B) real and erect
C) real, inverted and diminished
(D) real, inverted and of some size as the object.
(D) real, inverted and of same size as the object.

Question 15.
A plane mirror is approaching a person at a speed of 5 cm s-1. At what speed will his image approach him ?
(A) 10 cm s-1
(B) 5 cm s-1
(C) 20 cms-1
(D) 15 cm s-1
(A) 10 cms-1

Question 16.
An object is placed between two plane mirrors inclined at an angle of 30°, then total number of images formed is
(A) 12
(B) 2
(C) 11
(D) infinite
(C) 11

Question 17.
A ray is incident at an angle 38° with a mirror. The angle between normal and reflected ray is
(A) 38°
(B) 52°
(C) 90°
(D) 76°
(B) 52°

Question 18.
A concave mirror gives an image three times as large as the object placed at a distance of 420 cm from it. For the image to be real, the focal length should be
(A) 10 cm
(B) 15 cm
(C) 20 cm
(D) 30 cm
(B) 15 cm

Question 19.
A concave mirror of focal length f (in air) is immersed in water (μ=$$\frac{4}{3}$$). The focal length of the mirror in water will be
(A) f
(B) [altex]\frac{4}{3}[/latrex] f
(C) $$\frac{3{4}$$ f
(D) $$[\frac{7{3}$$ f
(A) f

Question 20.
A mirror produces magnified erect image of an object. The nature of mirror is
(A) convex
(B) concave
(C) neither convex nor concave
(D) plane
(B) concave

Question 21.
A ray of light is incident normally on a plane mirror. The angle of reflection will be
(A) 135°
(B) 90°
(C) 45°
(D) 0°
(D) 0°

Question 22.
The focal length f of a spherical mirror of radius of curvature R is
(A) $$\frac{R}{2}$$
(B) R
(C) $$\frac{3}{2}$$ R
(D) 2 R
(A) $$\frac{R}{2}$$

Question 23.
In which of the following cases, man will not see image greater than himself ?
(A) Concave mirror
(B) Convex mirror
(C) Plane and Concave
(D) None of these.
(B) Convex mirror

Question 24.
If an object is 30 cm away from a cancave mirror of focal length 15 cm, the image will be
(A) erect
(B) virtual
(C) diminished
(D) of same size
Ans:
(D) of same size

Question 25.
The number of images observable between two parallel plane mirrors is
(A) 2
(B) 4
(C) 11
(D) infinite
Ans:
(D) infinite

Question 26.
The focal length of a canvex lens is 30 cm and the size of image is a quarter of the object, then the object distance is
(A) 90 cm
(B) 60 cm
(C) 30 cm
(D) 40 cm
Ans:
(A) 90 cm

Question 27.
Focal length of a convex lens will be maximum for
(A) blue light
(B) yellow light
(C) green light
(D) red light.
(D) red light

Question 28.
A lens is behaving as convex lens in air and concave in water then its refractive index is
(A) smaller than air
(B) greater than both air and water
(C) greater than air, but less than water
(D) almost equal to water.
(C) greater than air, but less than water

Question 29.
The plane surface of a plano-convex lens of focal length f is silvered. It will behave as
(A) plane mirror
(B) convex mirror of focal length 2f
(C) concave mirror of focal length f/2
(D) None of the above
(C) concave mirror of focal length f2

Question 30.
Mirage is a phenomenon due to
(A) reflection of light
(B) refraction of light
(C) total internal reflection of light
(D) diffraction of light.
(C) total internal reflection of light.

Question 31.
The principle behind optical fibres is
(A) total internal reflection
(B) total external reflection
(C) both (A) and (B)
(D) diffraction.
(A) total internal reflection.

Question 32.
A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will
(A) become zero
(B) become infinite
(C) reduce
(D) increase
(B) become infinite

Question 33.
A convex lens will become less convergent in
(A) oil
(B) water
(C) both
(D) none
(B) water

Question 34.
Which of the following colours suffers maximum deviation in a prism?
(A) yellow
(B) blue
(C) green
(D) orange
(B) blue

Question 35.
The splitting of white light into several colours on passing through a glass prism is due to
(A) refraction
(B) reflection
(C) interference
(D) diffraction
(A) refraction

Question 36.
Rainbow is formed due to a combination of
(A) refraction and absorption
(B) dispersion and focussing
(C) refraction and scattering
(D) dispersion and total internal reflection
(D) dispersion and tota’ internal reflection

Question 37.
Which of the prism is used to see infrared spectrum of light ?
(A) rock salt
(B) nicol
(C) flint
(D) crown
(A) rock salt

Question 38.
Myopia is due to
(A) older age
(B) shortening of eye ball
(C) irregular change in focal length
(D) elongation of eye ball.
(D) elongation of eve ball

Question 39.
A person cannot see objects clearly beyond 2 m. The power of lens required to correct his vision will be
(A) +2 D
(B) -1 D
(C) +1 D
(D) -0.5 D
(D) -0.5 D

Question 40.
A person uses spectacle of power +2D. He is suffering from
(A) short sightedness of myopia
(B) long sightedness of hypermetropia
(C) presbyopia
(D) astigmatism
(B) long sighteciness of hypermetropia

Question 41.
Which of the following materials cannot be used to make a lens ?
(A) water
(B) glass
(C) clay
(D) plastic
(C) clay

Question 42.
No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be :
(A) plane only
(B) concave only
(C) convex only
(D) eighter plane or convex
(D) eighter plane or convex

Question 43.
A ray of light suffers refraction through an equilateral prism. The deviation produced by the prism does not depend on the :
(A) angle of incidence
(B) colour of light
(C) size of the prism
(D) material of the prism
(C) stze of the prism

Question 44.
A ray of light incident on a lens parrallel to its principal axis, after refraction passes through or appears to come from :
(A) its second focus
(B) its first focus
(C) its optical centre
(D) the centre of curvature of its second surface
(A) its second fucus

Question 45.
The source of ultra-violet light is :
(A) electric bulb
(B) carbon arc lamp
(C) red hot iron bulb
(D) sodium vapour lamp
(B) carbon arc lamp.

Question 46.
A mirror having a very wide fleld of view must be
(A) concave
(B) convex
(C) plane
(D) none of these
(B) convex

Question 47.
Linear magnification (m) of a convex mirror is :
(A) greater than one
(B) less than one
(C) zero
(D) equal to one
(B) less than one

Question 48.
Back side of a shining stainless steel spoon resembles :
(A) a concave mirror
(B) a convex mirror
(C) a plane mirror
(D) a prism
(B) a convex mirror

Question 49.
Front side of a shining stainless steel spoon resembles
(A) a concave mirror
(B) a convex mirror
(C) a plane mirror
(D) a prism
(A) concave mirror

Question 50.
If a concave mirror having focal length f is immersed in water (\mu=\frac{4{3), then the new focal length would be :
(A) $$\frac{4}{3}$$ f
(B) $$\frac{3}{4}$$ f
(C) f
(D) $$\frac{7}{4}$$ f
(C) f

Question 51.
Snell’s law is not valid when the angle of incidence is :
(A) 0°
(B) 45°
(C) 60°
(D) 90°
(A) 0°

Question 52.
Refraction is caused by :
(A) different wave speeds
(B) more than one reflection
(C) displaced images
(D) bending
(A) different wave speeds

Question 53.
A swimming pool appears to be 2 m deep. It’s actual depth is (\mu for water = 1.33)
(A) 2.66 m
(B) 2 m
(C) 2.34 m
(D) 2.54 m
(A) 2.66 m

Question 54.
Which one of the following can not be used to make a lens?
(A) water
(B) transparent plastic
(C) glass
(D) iron
(D) iron

Question 55.
The power of comblnation of two lenses of power +1.5D and -2.5 D is :
(A) -D
(B) 4 D
(C) +4 D
(D) +D
(A) -D

Question 56.
The size of the pupil is adjusted by :
(A) cornea
(B) iris
(C) retina
(D) aqueous human
(B) iris

Question 57.
The power of a lens is -1.5 D. It’s focal length is :
(A) -1.5 cm
(B) -15 cm
(C) 66.6 cm
(D) -66.6 cm
(D) -66.6 cm

Question 58.
The colour of light which suffers maximum bending while passing through a glass prism is :
(A) green
(B) red
(C) yellow
(D) violet
(D) violet

Question 59.
The three primary colours are :
(A) red, blue, yellow
(B) red, green, yellow
(C) yellow, green, orange
(D) red, green, blue
(D) red, green, blue

Question 60.
The colour of an object is the same as the light that is:
(A) transmitted
(B) absorbed
(C) reflected
(D) All of these
(C) reflected

Question 61.
Compared to ultraviolet waves, the wave length of infrared waves is:
(A) shorter
(B) longer
(C) the same
(D) faster
(B) longer

Question 62.
If there were no atmosphere, the cloudless sky would have appeared
(A) blue
(B) violet
(C) red
(D) black
(d) black

Fill in the blanks :

1. A convex lens is called a _______ lens.
converging

2. The middle colour is _______.
yellow

3. Yellow and blue colours are _______ colours of each other.
complementary

4. Maggenta colour is made by mixing red and ______ colour.
blue

5. Red flower appears ______ in green light.
black

6. During dispersion of light, which light is splitting up into ______ colours.
seven

7. A __________ lens is used as a magnifying glass.
convex

8. A beam of rays of light parallel to the principal axis of a convex lens, will passes through the ______ focus after refraction.
principal

9. The elementary colours white light are arranged in order of _______.
wave length

10. The band of different colours obtained due to dispersion of white light is called the _______.
spectrum

11. ______ first observed the dispersion of white light.
Sir Issac Newton

12. Starting from the violet and writing the first latter of the seven colours of the spectrum it is called _______.
VIBGYOR

13. The lens which is thinner at the centre and wider at the two edges is known as a _______ lens.
convex

14. Lenses are generally of two types, concave and ______.
convex

15. If a ray be incident on a convex lens parallel to its principal axis, then the refracted ray through the lens passes through the ______ of the lens.
focus.

16. The straight line joins the centres of the spherical surfaces forming the lens is called the _______ axis of the lens.
principal

17. The distance of the principal focus from the optical centre of a lens is called its principal ______ length.
focal

18. An object place perpendicular to the principal axis of a convex lens will have its image _______ to the principal axis.
Perpendicular

19. A transparent body absorbs all the colours of white light except the light of colour of its _______.
own

20. Yellow colour is a _______ colour.
secondary.

21. The light which consists of only one colour is called ______ light.
monochromatic

22. A convex mirror always produces a ______ Image.
virtual

23. Refractive index of a medium depends upon ________ of the light.
colour.

24. A red flower apprears ______ in green light.
black

25. The sky appears blue due to ______ of light.
sca tteroing

26. In human eye the image is formed on _______.
retina

27. A ________ mirror is used as a shaving mirror.
infinity

28. The radius of curvature of a spherical mirror is 20 cm. Its focal length is ______ cm.
10

29. ______ In 1841 was the first to give a systematic analysis of formation of images under paraxial approximation.
Gauss

30. Only rays inclined at an angle less than about _______ to the principal axis is considered as paraxial rays.
10°

31. The radius of curvature of a convex mirror is ______ Its focal length.
twice

32. As angle of prism increases, angle of deviation ______.
increases

33. When for a particular angle of incidence, the angle of deviation is minimum, the position is known as ______ position of the prism.
minimum deviation

34. In case of a rectangular glass slab, the emergent ray is _______ to the incident ray.
parallel

35. Refractive index of a gas _______ with increase in temperature.
decreases

36. Speed of light in water is lesser than that in air. Hence, air is optically ______ medlum.
rarer

37. Magnification produced by a concave lens is always _______.
positive

38. If a person walking in a dark room enters into a brightly lit corridor, the pupil of the eye ______.
contracts

39. ______ is a hole in the middle of iris.
Pupil

40. _______ lens is used as eye-lens in Galllean telescope.
Concave

41. When the object is stuated at 2 F1 (i.e. at twice the distance of focal length) from a convex lens, the image formed is real and ______.
inverted

42. When a red’ flower is viewed in green light it appeans _____.
black.

43. _____ discovered the dispersion of light by a prism.
Newton

44. Among the visible light, _______ coloured light is deviated the least.
red

45. ______ are used for studying crystal structure of solids.
X-rays

46. ______ rays are used in radio-therapy.
Gamma

47. The part of light we can see with our eyes is called _______ spectrum.
visible

State whether the following statement is True or False : VSA

1. Concave mirror is used as a rear vlew mirror in cars.
False

2. The radius of curvature of a convex mirror is twice its focal length.
True

3. The image formed by a convex mirror is inverted and magnified.
False

4. Both magnified and diminished image of an object can be formed using a concave mirror.
True

5. Speed of light decreases with increase in temperature.
False

6. Refractive index of a medium can be less than 1 .
False

7. Only the refracting surfaces of a prism need to be transparent.
True

8. Myopia is caused due to high converging power of eye-lens.
True

9. Cone cells cause the sensation of colour of objects in our eye.
True

10. Iris has no colour of its own.
False

11. Yellow is referred to as the mean colour.
True

12. A rectangular glass slab also produces dispersion of light.
False

13. A prism itself produces no colours.
True

14. Higher the wave length of light, lower will be its frequency.