Light – Multiple Choice Questions

Q1. Which vitamin’s deficiency over a period of time may result in night blindness?

  • Vitamin A
  • Vitamin B
  • Vitamin C
  • Vitamin D

Solution

Vitamin A deficiency over a period of time may result in night blindness.

Q2. Tears help our eyes by

  • Washing away salts
  • Keeping them from drying out
  • Keeping sun rays out
  • Cleaning the retina

Solution

Tears help our eyes by keeping them moist.

Q3. A material that allows light to pass through it without significant distortion is known as

  • Translucent
  • Opaque
  • Luminous
  • Transparent

Solution

A material that allows light to pass through it without significant distortion is known as transparent.

Q4. Where is the vitreous humour located in the human eye?

  • Between the lens and retina
  • Between the lens and cornea
  • Between the cornea and retina
  • Outside the eye

Solution

The vitreous humour is located between the lens and retina in the human eye.

Q5. Within what time after death the eyes must be removed?

  • 4-6 hours
  • 4-6 days
  • 24 hours
  • 10 days

Solution

4-6 hours after death the eyes must be removed.

Q6. In a dark room a parallel beam of light falls on a white wall and the reflected light can be seen from anywhere because

  • Wall is a rough surface and irregular reflection takes place from its surface
  • Wall is a rough surface and regular reflection takes place from its surface
  • Wall is a smooth surface and irregular reflection takes place from its surface
  • Wall is a smooth surface and regular reflection takes place from its surface

Solution

Wall is a rough surface and irregular reflection takes place from its surface and light is diffused in all directions.

Q7. The change in focal length of an eye lens to focus the image of objects at varying distances is done by the action of

  • Retina
  • Pupil
  • Ciliary muscles
  • Iris

Solution

Ciliary muscles expand or contract to adjust the size of the eye lens ; so as to form the final image on the retina.

Q8. If we raise our right hand in front of a mirror

  • The right hand of the image is lifted
  • The left hand of the image is lifted
  • Two images of the left hand are formed
  • Multiple images are formed

Solution

The image formed by the plane mirror undergoes lateral inversion. So, right becomes left and left becomes right.

Q9. In a lateral inversion

  • The left side of the object becomes the right side of the image and vice-versa
  • The right side of the object remains the right side of the image
  • The left side of the object remains the left side of the image
  • show of the above

Solution

In a lateral inversion, the left side of the object becomes the right side of the image and vice-versa.

Q10. Two plane mirrors are arranged parallel and facing each other at some separation. How many images are formed for a point source kept in between them?

  • 3
  • 4
  • 5
  • infinite

Solution

Infinite images will be formed when two mirrors are parallel to each other.

Q11. Based on visual character, the normal line is

  • Dotted
  • Real
  • Imaginary
  • Inverted

Solution

Normal to the reflecting surface at a point is an imaginary line making an angle of 90º to the line representing the mirror at the point where the incident ray strikes the mirror. 

Q12. Image formed by a plane mirror is

  • Virtual, behind the mirror and enlarged
  • Virtual, behind the mirror and of the same size as the object
  • Real at the surface of the mirror and enlarged
  • Real, behind the mirror and of the same size as the object

Solution

Image formed by a plane mirror is virtual, behind the mirror and of the same size as the object.

Q13. The idea of using a number of mirrors at an angle to one another is used in a

  • Binocular
  • Kaleidoscope
  • Telescope
  • Opthalmometer

Solution

The idea of using a number of mirrors at an angle to one another is used in a kaleidoscope.

Q14. We can see an object only when the light may have been

  • Emitted by the object
  • Reflected by the object
  • Emitted or reflected by the object
  • Absorbed by the object

Solution

It is only when light from an object enters our eyes that we see the object. The light may have been emitted by the object or may have been reflected by it.

Q15. The human eye forms the image of an object at its

  • Cornea
  • Iris
  • Pupil
  • Retina

Solution

The human eye forms the image of an object at its retina.

Q16. The phenomenon in which white light splits into seven colours is

  • Spectrum 
  • Reflection   
  • Refraction    
  • Dispersion

Solution

The phenomenon in which white light split into seven colours is called dispersion.

Q17.

Who cannot donate eyes?

  • A female
  • A person using spectacles
  • People suffering from AIDS, Hepatitis B or C, etc
  • A person with Myopia

Solution

People suffering from AIDS, Hepatitis B or C, rabies, leukemia, tetanus, cholera, encephalitis cannot donate eyes.

Q18. Which of the following materials is opaque for light?

  • Water
  • Glass
  • Plastic
  • Clay

Solution

Clay is opaque for light.

Q19. Cataract is generally due to

  • Older age       
  • Change in focal length      
  • Shortening of the eyeball
  • Elongation of the eyeball

Solution

In old age, eyesight becomes foggy. It is due to the eye lens becoming cloudy. When it happens, persons are said to have cataract.

Q20.

What device is used to correct eye defects?

  • Mirror
  • Glass slab
  • Lenses
  • Microscope

Solution

Lenses are used to correct eye defects.

Q21. A defect of eye which results when the lens loses its transparency

  • Presbyopia
  • Cataract
  • Conjunctivitis
  • Myopia

Solution

A defect of eye which results when the lens loses its transparency is cataract.

Q22. Rahul is standing in front of a mirror at a distance of 15 m. With respect to himself, his image will form at a distance of

  • 90 m
  • 60 m
  • 30 m
  • 15 m

Solution

In plane mirrors, the image appears at the same distance behind the mirror as the object was in front of it. So, with respect to the mirror, his image will be 15 m away. Hence, with respect to himself, the image is 30 m away.

Q23. The image formed by the eye lens on the retina is

  • Real, upright and enlarged
  • Real, upright and diminished
  • Real, inverted and diminished
  • Virtual, inverted and diminished

Solution

The image formed by the eye lens on the retina is real, inverted, diminished.

Q24. Which part of the eye gives it a distinctive color?

  • Pupil
  • Iris
  • Retina
  • Cornea

Solution

The iris is the part of that eye which gives it its distinctive colour.

Q25.

Who invented a system of reading and writing used by people who are blind or visually impaired.

  • Louis Philippe
  • Louis Braille
  • Nikola Tesla
  • Carl Sagan

Solution

Louis Braille invented a system of reading and writing used by people who are blind or visually impaired.

Q26. Rods in the human eye are sensitive to

  • Dim light
  • Bright light
  • Dark light
  • No light

Solution

Rods in the human eye are sensitive to dim light.

Q27. Pick the odd one out.

  • Iris
  • Cornea
  • Eustachian tube
  • Pupil

Solution

Eustachian tube is not a part of the eye.

Q28. Blind spot develops at the junction of optic nerves and the

  • Iris
  • Pupil
  • Retina
  • Eyelid

Solution

At the junction of the optic nerve and the retina, there are no sensory cells, hence, it is impossible to gain an image on that spot. This spot is called the blind spot.

Q29. Which of the following correctly states the law of reflection?

  • The angle of incidence, the angle of reflection and the normal at the point of incidence, lie in the same plane
  • The incident ray, the reflected ray and the normal at the point of incidence, lie in the same plane
  • The angle of incidence is not equal to the angle of reflection
  • The angle of incidence is nearly equal to the angle of reflection

Solution

The incident ray, the reflected ray and the normal at the point of incidence, lie in the same plane.

Q30. The bodies which shine in the light of other objects are called

  • Illuminating body
  • Illuminated body
  • Planet
  • Star

Solution

The objects which shine in the light of other objects are called illuminated objects.

Q31. Which of the following is the richest source of Vitamin A?

  • Onions
  • Liver
  • Mushrooms
  • Cashews

Solution

Liver is the richest source of vitamin A.

Q32. A ray of light is incident on a plane mirror and the angle of reflection is 50o. The angle incidence is

  • 50o
  • 25o
  • 90o
  • 100o

Solution

Angle of incidence = angle of reflection = 50o

Q33. The second law of reflection states that

  • The angle of incidence is sometimes equal to the angle of reflection
  • The angle of incidence is always equal to the angle of reflection
  • The angle of incidence is always equal to the angle of reflection only when the mirror is kept at an angle of 45o
  • The incident ray, the reflected and the normal at the point of incidence all lie in the same plane

Solution

The incident ray, the reflected and the normal at the point of incidence all lie in the same plane.

Q34. Sensations felt by the nerve cells are transmitted to the brain through the

  • Retina
  • Blind spot
  • Optic spot
  • Optic nerve

Solution

Sensations felt by the nerve cells are transmitted to the brain through the optic nerve.

Q35. Regular reflection takes place when a beam of light strikes

  • Chalk powder
  • Cardboard surface   
  • Concrete wall
  • Polished wooden table

Solution

Regular reflection takes place at smooth and polished surfaces.

Q36. For which part of the body carotenoids are useful?

  • Nose
  • Legs
  • Eyes
  • Stomach

Solution

Carotenoids are useful for eyes.

Q37. Eye lens is an example of

  • Concave lens
  • Convex lens
  • Plano-concave lens
  • Plano-convex lens

Solution

Eye lens is thicker at middle and thinner at the periphery. So, it is a convex lens.

Q38. The incident ray and the reflected ray from a mirror are mutually perpendicular to each other. The angle of incidence is

  • 90o
  • 45o
  • 22.5o
  • zero

Solution

  • Angle of incidence + Angle of reflection = 90o
  • Angle of incidence = Angle of reflection
  • ∴ 2 x Angle of incidence = 90o
  • ∴ Angle of incidence = 45o

Q39. When does diffused reflection take place?

  • When all the parallel rays reflected from a plane surface are parallel
  • When all the parallel rays reflected from a plane surface are not parallel
  • When all the parallel rays reflected from a plane surface are symmetric
  • show of the above

Solution

When all the parallel rays reflected from a plane surface are not parallel diffused reflection is said to take place.

Q40. The first law of reflection states that

  • The angle of incidence is sometimes equal to the angle of reflection
  • The angle of incidence is always equal to the angle of reflection
  • The angle of incidence is always equal to the angle of reflection only when the mirror is kept at an angle of 45o
  • The incident ray, the reflected and the normal at the point of incidence all lie in the same plane

Solution

The angle of incidence is always equal to the angle of reflection.