Class 10 Science NCERT MCQs Chapter 10 The Human Eye and the Colourful World
NCERT MCQs of Class 10 Science, Chapter 10 (The human eye and the colourful world)
1) What is the primary function of the human eye?
a) Hearing sounds
b) Detecting electromagnetic waves
c) Focusing light to form images
d) Producing sound
Answer: c) Focusing light to form images
Explanation: The human eye focuses light on the retina to form images that are processed by the brain.
2) What is the role of the iris in the eye?
a) To control the shape of the lens
b) To regulate the amount of light entering the eye
c) To produce tears
d) To focus light on the retina
Answer: b) To regulate the amount of light entering the eye
Explanation: The iris controls the size of the pupil, regulating the amount of light entering the eye.
3) What type of lens is present in the human eye?
a) Concave lens
b) Convex lens
c) Cylindrical lens
d) Plane lens
Answer: b) Convex lens
Explanation: The human eye contains a convex lens that converges light to focus images on the retina.
4) What is the far point of a normal human eye?
a) 10 cm
b) 25 cm
c) Infinite
d) 2 m
Answer: c) Infinite
Explanation: The far point of a normal human eye is at infinity, where distant objects are seen clearly.
5) Which part of the eye is responsible for converting light into electrical signals?
a) Retina
b) Cornea
c) Lens
d) Iris
Answer: a) Retina
Explanation: The retina contains photoreceptor cells (rods and cones) that convert light into electrical signals for the brain to interpret.
6) What is the near point of a normal human eye?
a) 10 cm
b) 25 cm
c) 20 cm
d) 50 cm
Answer: b) 25 cm
Explanation: The near point of a normal human eye is 25 cm, the closest distance at which objects can be seen clearly.
7) Which of the following is corrected using a concave lens?
a) Hypermetropia
b) Myopia
c) Cataract
d) Astigmatism
Answer: b) Myopia
Explanation: Myopia (short-sightedness) is corrected using a concave lens, which diverges light rays to focus them on the retina.
8) The defect in the eye where distant objects appear blurry is called:
a) Hypermetropia
b) Myopia
c) Cataract
d) Presbyopia
Answer: b) Myopia
Explanation: Myopia is a defect where distant objects appear blurry because the image forms in front of the retina.
9) What causes the sky to appear blue?
a) Reflection of sunlight
b) Scattering of light by atmospheric particles
c) Absorption of all colors except blue
d) Refraction of light through water droplets
Answer: b) Scattering of light by atmospheric particles
Explanation: Shorter wavelengths (blue light) scatter more in the atmosphere, making the sky appear blue.
10) Which phenomenon explains the reddish appearance of the Sun during sunrise and sunset?
a) Dispersion of light
b) Total internal reflection
c) Refraction of light
d) Scattering of light
Answer: d) Scattering of light
Explanation: At sunrise and sunset, light travels a longer distance through the atmosphere, scattering shorter wavelengths (blue) and leaving longer wavelengths (red) to dominate.
11) Which defect of the eye is characterized by the inability to focus on near objects?
a) Myopia
b) Hypermetropia
c) Astigmatism
d) Night blindness
Answer: b) Hypermetropia
Explanation: Hypermetropia (long-sightedness) is corrected using a convex lens to focus near objects on the retina.
12) The splitting of white light into its constituent colors is called:
a) Reflection
b) Dispersion
c) Refraction
d) Scattering
Answer: b) Dispersion
Explanation: Dispersion occurs when white light passes through a prism, separating into its constituent colors due to varying refractive indices.
13) What is the power of accommodation of the human eye?
a) The ability to focus on objects at different distances
b) The power of the eye lens to refract light
c) The ability of the retina to form an image
d) The power of the cornea to absorb light
Answer: a) The ability to focus on objects at different distances
Explanation: The power of accommodation refers to the eye’s ability to change the curvature of the lens to focus on objects at varying distances.
14) Which eye defect commonly occurs with aging?
a) Myopia
b) Hypermetropia
c) Cataract
d) Presbyopia
Answer: d) Presbyopia
Explanation: Presbyopia, caused by the weakening of ciliary muscles and lens flexibility, makes it difficult to focus on nearby objects and is common with aging.
15) Which type of lens is used to correct hypermetropia?
a) Concave lens
b) Convex lens
c) Cylindrical lens
d) Plane lens
Answer: b) Convex lens
Explanation: Hypermetropia is corrected using a convex lens, which converges light rays to focus on the retina.
16) What is the unit of the power of a lens?
a) Meter
b) Dioptre
c) Hertz
d) Candela
Answer: b) Dioptre
Explanation: The power of a lens is measured in dioptres (D), which is the reciprocal of the focal length in meters.
17) Why do stars appear to twinkle?
a) Reflection of starlight by Earth’s atmosphere
b) Dispersion of light in space
c) Refraction and atmospheric disturbances
d) Scattering of starlight
Answer: c) Refraction and atmospheric disturbances
Explanation: Stars twinkle due to the refraction of their light through Earth’s atmosphere, which is constantly changing.
18) Which phenomenon is responsible for the formation of a rainbow?
a) Dispersion, reflection, and refraction
b) Diffraction and refraction
c) Reflection and scattering
d) Total internal reflection and absorption
Answer: a) Dispersion, reflection, and refraction
Explanation: A rainbow forms when sunlight undergoes dispersion, reflection, and refraction through raindrops.
19) What is the near point of the eye for a person suffering from hypermetropia?
a) Less than 25 cm
b) Exactly 25 cm
c) Greater than 25 cm
d) Infinity
Answer: c) Greater than 25 cm
Explanation: In hypermetropia, the near point of the eye is farther than 25 cm, making it difficult to see nearby objects.
20) What happens to the lens of the eye when viewing a distant object?
a) Becomes thinner
b) Becomes thicker
c) Retains its shape
d) Moves forward
Answer: a) Becomes thinner
Explanation: When viewing distant objects, the ciliary muscles relax, causing the lens to become thinner for reduced refraction.
21) Which part of the eye is transparent and helps to focus light onto the retina?
a) Cornea
b) Iris
c) Pupil
d) Optic nerve
Answer: a) Cornea
Explanation: The cornea is the transparent, curved outer layer of the eye that helps focus light onto the retina.
22) What causes a cataract in the eye?
a) Loss of flexibility of the lens
b) Clouding of the eye lens
c) Weakening of ciliary muscles
d) Excessive refraction of light
Answer: b) Clouding of the eye lens
Explanation: Cataract occurs when the lens becomes cloudy, leading to blurred vision and, in severe cases, blindness.
23) Which condition is characterized by the inability to distinguish between certain colors?
a) Myopia
b) Hypermetropia
c) Color blindness
d) Astigmatism
Answer: c) Color blindness
Explanation: Color blindness is a genetic condition where individuals cannot distinguish between certain colors, often red and green.
24) The persistence of vision in the human eye is about:
a) 110\frac{1}{10}101 second
b) 116\frac{1}{16}161 second
c) 1 second
d) 5 seconds
Answer: b) 116\frac{1}{16}161 second
Explanation: Persistence of vision allows the human eye to retain an image for 116\frac{1}{16}161 second, enabling the perception of continuous motion in films.
25) What is the minimum distance for clear vision in a normal human eye?
a) 10 cm
b) 20 cm
c) 25 cm
d) 50 cm
Answer: c) 25 cm
Explanation: The minimum distance for clear vision in a normal eye is 25 cm, known as the near point.
26) What is astigmatism?
a) A condition caused by a cloudy lens
b) A defect due to an irregular curvature of the cornea or lens
c) The inability to focus on distant objects
d) An age-related loss of accommodation power
Answer: b) A defect due to an irregular curvature of the cornea or lens
Explanation: Astigmatism is caused by an irregular curvature of the cornea or lens, resulting in distorted or blurred vision.
27) Which color of light bends the least when passing through a prism?
a) Violet
b) Red
c) Green
d) Blue
Answer: b) Red
Explanation: Red light bends the least because it has the longest wavelength among visible light.
28) What does the power of accommodation of the eye depend on?
a) Flexibility of the iris
b) Thickness of the cornea
c) Ability of the lens to change its shape
d) Size of the pupil
Answer: c) Ability of the lens to change its shape
Explanation: The power of accommodation depends on the ability of the lens to adjust its shape to focus on objects at varying distances.
29) Which phenomenon is responsible for the formation of images in the eye?
a) Reflection
b) Refraction
c) Diffraction
d) Dispersion
Answer: b) Refraction
Explanation: Refraction of light through the eye’s lens system forms images on the retina.
30) What is the approximate focal length of the eye lens in its relaxed state?
a) 1 cm
b) 2.5 cm
c) 3 cm
d) 5 cm
Answer: b) 2.5 cm
Explanation: The focal length of the eye lens in its relaxed state is approximately 2.5 cm.
31) Why do distant stars appear to twinkle?
a) They are very far from the Earth.
b) Their brightness changes over time.
c) Atmospheric refraction causes their light to vary.
d) Their size is too small to observe clearly.
Answer: c) Atmospheric refraction causes their light to vary.
Explanation: Twinkling occurs due to continuous refraction of starlight in Earth's atmosphere, which is not uniform.
32) Which part of the eye controls the size of the pupil?
a) Retina
b) Cornea
c) Iris
d) Ciliary muscles
Answer: c) Iris
Explanation: The iris controls the size of the pupil, adjusting the amount of light entering the eye.
33) The condition where a person cannot see objects clearly at night is called:
a) Myopia
b) Presbyopia
c) Night blindness
d) Astigmatism
Answer: c) Night blindness
Explanation: Night blindness is caused by a deficiency of vitamin A, affecting the ability to see in low light.
34) Why is the danger signal light red?
a) Red light is soothing to the eyes.
b) Red light is least scattered and can travel long distances.
c) Red light is highly scattered.
d) Red light is absorbed easily.
Answer: b) Red light is least scattered and can travel long distances.
Explanation: Red light has the longest wavelength, so it is scattered the least and remains visible over long distances.
35) What type of image is formed on the retina?
a) Real and inverted
b) Virtual and inverted
c) Virtual and erect
d) Real and erect
Answer: a) Real and inverted
Explanation: The lens of the eye forms a real and inverted image on the retina.
36) Which color of light scatters the most in the atmosphere?
a) Red
b) Violet
c) Green
d) Yellow
Answer: b) Violet
Explanation: Violet light scatters the most because it has the shortest wavelength in the visible spectrum.
37) Which type of lens is used in spectacles for people with presbyopia?
a) Convex lens
b) Concave lens
c) Cylindrical lens
d) Bifocal lens
Answer: d) Bifocal lens
Explanation: Bifocal lenses are used to correct presbyopia as they provide two different focal lengths for near and distant vision.
38) Which condition can be corrected by using cylindrical lenses?
a) Myopia
b) Hypermetropia
c) Astigmatism
d) Cataract
Answer: c) Astigmatism
Explanation: Cylindrical lenses are used to correct astigmatism by compensating for irregular curvature of the cornea.
39) The splitting of sunlight into seven colors by a prism is called:
a) Diffraction
b) Dispersion
c) Refraction
d) Scattering
Answer: b) Dispersion
Explanation: Dispersion is the splitting of white light into its constituent colors when passing through a prism.
40) What causes a rainbow to form?
a) Scattering of light
b) Reflection inside raindrops
c) Refraction and dispersion of sunlight in raindrops
d) Total internal reflection in clouds
Answer: c) Refraction and dispersion of sunlight in raindrops
Explanation: A rainbow forms when sunlight undergoes refraction, dispersion, and reflection inside raindrops.
41) What happens to the pupil of the eye in bright light?
a) It becomes smaller.
b) It becomes larger.
c) It remains unchanged.
d) It moves backward.
Answer: a) It becomes smaller.
Explanation: In bright light, the pupil contracts to reduce the amount of light entering the eye and protect the retina.42) Which part of the eye maintains its shape and protects internal components?
a) Retina
b) Cornea
c) Sclera
d) Optic nerve
Answer: c) Sclera
Explanation: The sclera is the white, tough outer layer of the eye that provides protection and structural support.43) Which phenomenon explains the formation of a mirage?
a) Reflection
b) Refraction
c) Total internal reflection
d) Scattering
Answer: c) Total internal reflection
Explanation: A mirage occurs due to total internal reflection of light in layers of air with varying temperatures and densities.44) Why does the Sun appear reddish at sunrise and sunset?
a) Only red light passes through the atmosphere.
b) Red light has the longest wavelength and scatters the least.
c) Red light is absorbed by the atmosphere.
d) Blue light is refracted more.
Answer: b) Red light has the longest wavelength and scatters the least.
Explanation: During sunrise and sunset, light travels a longer distance through the atmosphere, scattering shorter wavelengths and leaving red as the dominant color.45) What causes presbyopia?
a) Weakening of ciliary muscles and loss of lens flexibility
b) Clouding of the lens
c) Irregular shape of the cornea
d) Lack of vitamin A
Answer: a) Weakening of ciliary muscles and loss of lens flexibility
Explanation: Presbyopia is an age-related condition caused by reduced flexibility of the lens and weakening of ciliary muscles.46) Which type of light scattering is responsible for the blue color of the sky?
a) Rayleigh scattering
b) Mie scattering
c) Dispersion
d) Reflection
Answer: a) Rayleigh scattering
Explanation: Rayleigh scattering occurs when light interacts with particles smaller than its wavelength, scattering shorter wavelengths like blue.47) What is the main role of the optic nerve in the eye?
a) To regulate the amount of light entering the eye
b) To focus light onto the retina
c) To carry visual signals to the brain
d) To supply nutrients to the eye
Answer: c) To carry visual signals to the brain
Explanation: The optic nerve transmits electrical signals from the retina to the brain for image processing.48) Which phenomenon allows us to see objects around corners using mirrors?
a) Reflection
b) Refraction
c) Dispersion
d) Diffraction
Answer: a) Reflection
Explanation: Reflection of light from mirrors allows us to change the direction of light and see objects around corners.49) Which color of light refracts the most when passing through a prism?
a) Red
b) Yellow
c) Violet
d) Green
Answer: c) Violet
Explanation: Violet light has the shortest wavelength, so it refracts the most when passing through a prism.50) What causes the splitting of light in a prism?
a) Different colors have the same speed in the prism.
b) Different colors travel at different speeds in the prism.
c) Only red light refracts.
d) Light is absorbed by the prism.
Answer: b) Different colors travel at different speeds in the prism.
Explanation: Dispersion occurs because different colors of light have different refractive indices in the prism.51) What type of lenses are used in magnifying glasses?
a) Concave lenses
b) Convex lenses
c) Cylindrical lenses
d) Bifocal lenses
Answer: b) Convex lenses
Explanation: Convex lenses converge light and magnify objects, making them suitable for magnifying glasses.52) What is the power of a lens with a focal length of -50 cm?
a) -2 D
b) 2 D
c) -0.5 D
d) 5 D
Answer: a) -2 D
Explanation: Power (P) is given by P=1/f. For f=−50 cm = -0.05m
P=1/(-0.05) = -2D53) Which eye defect involves the inability to see both near and distant objects clearly?
a) Myopia
b) Hypermetropia
c) Presbyopia
d) Astigmatism
Answer: c) Presbyopia
Explanation: Presbyopia affects near and distant vision due to reduced flexibility of the lens with age.54) What is the angle of deviation in a prism?
a) The angle between the incident ray and the prism surface
b) The angle between the refracted ray and the normal
c) The angle between the incident ray and the emergent ray
d) The angle of refraction inside the prism
Answer: c) The angle between the incident ray and the emergent ray
Explanation: The angle of deviation is the angle between the direction of the incident ray and the emergent ray after passing through a prism.55) What does the term "least distance of distinct vision" mean?
a) The shortest distance at which the eye can see clearly
b) The farthest distance at which the eye can see clearly
c) The distance from the cornea to the retina
d) The diameter of the pupil
Answer: a) The shortest distance at which the eye can see clearly
Explanation: The least distance of distinct vision for a normal eye is 25 cm.56) Which light phenomenon explains why the Sun appears white at noon?
a) Reflection
b) Refraction
c) Dispersion
d) Scattering
Answer: d) Scattering
Explanation: At noon, the Sun’s light travels a shorter distance through the atmosphere, scattering all colors almost equally, making the Sun appear white.57) What is the unit of focal length?
a) Dioptre
b) Meter
c) Candela
d) Newton
Answer: b) Meter
Explanation: Focal length is measured in meters in the SI system.58) Which condition requires bifocal lenses for correction?
a) Myopia
b) Hypermetropia
c) Presbyopia
d) Astigmatism
Answer: c) Presbyopia
Explanation: Bifocal lenses correct presbyopia by providing two focal lengths for near and distant vision.59) Which color of light has the longest wavelength?
a) Red
b) Green
c) Blue
d) Violet
Answer: a) Red
Explanation: Red light has the longest wavelength, which is why it scatters the least in the atmosphere.60) What happens to light when it enters a denser medium?
a) It speeds up.
b) It slows down.
c) It reflects entirely.
d) It stops propagating.
Answer: b) It slows down.
Explanation: Light slows down when it enters a denser medium due to increased optical density.
MCQs from the Exercise part of the chapter
1) The human eye can focus on objects at different distances by adjusting the focal length of the eye lens. This is due to:
a) Presbyopia
b) Accommodation
c) Near-sightedness
d)
Far-sightedness
Answer: b) Accommodation
Explanation:
The human eye can adjust the focal length of its lens due to the
action of ciliary muscles, enabling it to focus on objects at varying
distances.
2) The human eye forms the image of an object at its:
a) Cornea
b) Iris
c) Pupil
d) Retina
Answer: d) Retina
Explanation:
The retina is the light-sensitive layer of the eye where the lens
forms a real and inverted image of the object.
3) The least distance of distinct vision for a young adult with normal vision is about:
a) 25 m
b) 2.5 cm
c) 25 cm
d) 2.5 m
Answer: c) 25 cm
Explanation:
The least distance of distinct vision for a normal eye is
approximately 25 cm, known as the near point.
4) The change in focal length of an eye lens is caused by the action of the:
a) Pupil
b) Retina
c) Ciliary muscles
d) Iris
Answer: c) Ciliary muscles
Explanation:
The ciliary muscles adjust the curvature of the eye lens, altering
its focal length to focus on near or distant objects.
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