The Human Eye and the Colourful World · Class 10 Science: 219 MCQs with answers

Q1. The part of the eye where MOST refraction of light occurs is the:

Q2. A cataract is a condition in which:

Q3. Cataract is cured by:

Q4. What is meant by the power of accommodation of the eye?

Q5. Why does the pupil of the eye change its size?

Q6. Where is the image formed in the human eye? State its nature.

Q7. What are rods and cones? State one function of each.

Q8. What is a cataract? How is it treated?

Q9. Give three advantages of our having two eyes instead of one.

Q10. A person can read a book but cannot clearly see a bus far down the road. The defect is:

Q11. In a myopic eye, the image of a distant object forms:

Q12. In hypermetropia, the near point:

Q13. In myopia, the far point:

Q14. One cause of myopia is an eyeball that is:

Q15. One cause of hypermetropia is an eye lens with focal length:

Q16. Presbyopia is mainly caused by:

Q17. Bifocal lenses have:

Q18. A person holds the newspaper at arm's length to read. The likely defect is:

Q19. What is myopia? State its two causes.

Q20. What is hypermetropia? State its two causes.

Q21. Why do some people need bifocal lenses? Describe their construction.

Q22. Which colour deviates the MOST while passing through a prism?

Q23. Which colour deviates the LEAST?

Q24. To see a rainbow, the Sun must be:

Q25. Newton recombined the spectrum into white light using:

Q26. What is dispersion of white light? What is the cause of dispersion?

Q27. Define the angle of deviation for a prism.

Q28. Which colour of white light deviates the most and which the least on passing through a prism? Give the reason.

Q29. Name four factors on which the angle of deviation of a prism depends.

Q30. Planets do not twinkle because they:

Q31. Which colour of light is scattered the MOST by air molecules?

Q32. Which colour is scattered the LEAST?

Q33. The blue colour of the sky is due to:

Q34. The red colour of the Sun at sunrise/sunset is because:

Q35. 'Danger' signal lights are red because red light:

Q36. To an astronaut in space, the sky appears:

Q37. Which is an example of the Tyndall effect?

Q38. Consider these statements about the image formed on the retina. I. It is real. II. It is inverted. III. It is diminished. IV. The brain turns it the right way up. Which statements are correct?

Q39. A person walks from bright sunshine into a dim room and for a few seconds sees almost nothing. The structure responsible for the adjustment that follows is the:

Q40. The pupil contracts in bright sunlight because:

Q41. In the comparison between an eye and a camera, the part of the camera that plays the same role as the retina is the:

Q42. A normal eye can see clearly over the range:

Q43. When you look at a distant mountain, your ciliary muscles are:

Q44. When the eye views a NEARBY object, the focal length of its lens:

Q45. While the eye accommodates, which distance stays CONSTANT?

Q46. A camera focuses by moving its lens. The eye focuses by:

Q47. When you enter a dark room from bright sunlight, you cannot see at first because:

Q48. A book held 30 cm from a normal eye can be read comfortably, but at 10 cm it cannot, because:

Q49. Which sequence correctly traces light through the eye?

Q50. The main advantage of having eyes on the FRONT of the face (like humans) is:

Q51. Nocturnal animals (like owls) see well at night mainly because their retinas are rich in:

Q52. During accommodation for NEAR vision, which sequence is correct?

Q53. If the ciliary muscles are fully relaxed, the eye is focused on:

Q54. The iris of the eye is comparable to which camera part?

Q55. The aqueous humour is located between the:

Q56. A person cannot read a newspaper held closer than 25 cm comfortably, even with a normal eye. Explain why.

Q57. How does the eye adjust when a student looks up from a book to the blackboard?

Q58. State two differences between the working of the eye and of a camera.

Q59. Why is a person momentarily 'blind' on entering a dark room from bright sunlight?

Q60. Draw a labelled description of the human eye and explain the function of each main part: cornea, iris, pupil, crystalline lens, ciliary muscles, retina and optic nerve.

Q61. An elderly villager complains that everything looks like seeing through fog, and light lamps show halos; a doctor says his eye lens has turned milky. Name the condition, explain what has happened inside the eye, why spectacles will not help, and how it can be treated. Also state why he should not delay.

Q62. A person can read a road sign across the street but cannot read a book at 25 cm. The lens prescribed will be:

Q63. A lens of focal length 20 cm has a power of:

Q64. A prescription of −2 D means the lens is:

Q65. The far point of a myopic person is 1.5 m. The correcting lens has focal length:

Q66. For that person (far point 1.5 m), the power of the lens is about:

Q67. A myopic person's far point is 50 cm. The power of the correcting lens is:

Q68. The concave lens prescribed for myopia forms the image of a distant object:

Q69. The convex lens prescribed for reading in hypermetropia forms the image of a book at 25 cm:

Q70. A lens of focal length +40 cm has power:

Q71. Which prescription belongs to a hypermetropic person?

Q72. A student in the last bench squints at the board but reads his notebook easily. As he grows without correction, his far point will likely:

Q73. Two thin lenses of powers +3 D and −1 D are in contact. The combination has power:

Q74. The image formed by the correcting lens (for both defects) is always:

Q75. A person needs +1 D for reading and −2 D for distance. He should use:

Q76. The hypermetropic eye can still see distant objects clearly because:

Q77. A person's spectacles have the number +0.75 D printed on them. Without them, the person struggles to:

Q78. How does a concave lens correct myopia? Answer with the image it forms.

Q79. How does a convex lens help a hypermetropic person read at 25 cm?

Q80. The far point of a myopic person is 120 cm. Calculate the focal length and power of the required lens.

Q81. What is presbyopia? How does it differ from hypermetropia?

Q82. A lens prescription says −1.75 D. What can you conclude about the lens and the person's eyesight?

Q83. White light passes through a prism and lands on a screen. What is seen on the screen is:

Q84. Which group lists three colours in the order they appear in a spectrum, moving from the violet end?

Q85. The emergent ray of a glass SLAB is parallel to the incident ray, but a prism's is not, because:

Q86. In glass, the refractive index is HIGHEST for:

Q87. In the spectrum cast on a wall by a prism held base-down, the TOP colour is:

Q88. Which colour of light travels FASTEST inside glass?

Q89. Which quantity is the SAME for all colours inside glass?

Q90. The correct sequence of events in a raindrop forming a rainbow is:

Q91. A rainbow seen in the EVENING will appear towards the:

Q92. The dispersion of light through a prism proves that:

Q93. If a beam of pure RED light passes through a prism, it will:

Q94. Which factor does NOT affect the angle of deviation?

Q95. The 'fire' seen in a diamond is mainly due to its:

Q96. Two prisms are placed together, the second inverted, as in Newton's setup. A narrow beam of sunlight passes through both. The light emerging from the second prism is:

Q97. Monochromatic light means light:

Q98. The angle of emergence of a prism is the angle between the:

Q99. Why do the two refractions in a glass slab produce no net deviation, while those in a prism do?

Q100. Describe Newton's experiment with two prisms and state its conclusion.

Q101. List, in order, what happens to a ray of sunlight inside a raindrop that contributes to a rainbow.

Q102. A beam of green light passes through a prism. Will it disperse? Will it deviate? Explain.

Q103. With a labelled description of the path of a monochromatic ray through a triangular glass prism, define angle of incidence, angle of refraction, angle of emergence and angle of deviation, and explain why the deviation occurs at all.

Q104. Atmospheric refraction lets us see the Sun about two minutes early and about two minutes late. The day is therefore lengthened by about:

Q105. The refractive index of air near the ground compared with air high up is:

Q106. The flattened (oval) appearance of the rising Sun is because:

Q107. Stars near the HORIZON twinkle more than stars overhead because their light:

Q108. Clouds appear white because their droplets:

Q109. The sky would NOT be blue if:

Q110. Which phenomenon does NOT involve atmospheric refraction?

Q111. Fine dust and smoke particles in a room make a projector beam visible. The light reaching your eye from the beam's path is:

Q112. If the Earth's atmosphere suddenly became much denser, the apparent day length would:

Q113. During a total solar eclipse from the Moon's surface, the sky around the Sun would look:

Q114. A student holds a book steadily closer until the print blurs. For a normal young eye this happens at about 25 cm, because at that distance:

Q115. The eye keeps its lens in a fixed position yet focuses objects at many distances. It manages this by:

Q116. A student reading a book looks up at a distant hill. At that moment the ciliary muscles:

Q117. Every eye has a small blind spot. It exists at the place where:

Q118. A garden seen by moonlight looks grey rather than coloured. This is because in dim light the eye is relying mainly on:

Q119. The pupil looks black even in bright sunlight because:

Q120. Which group lists the parts light passes through, in the correct order, on its way into the eye?

Q121. The eye lens differs from an ordinary glass convex lens chiefly in that it:

Q122. The eyeball is roughly 2.3 cm across, and the lens-to-retina distance is fixed at about that value. The consequence for focusing is that:

Q123. An object is moved from 5 m away to 30 cm away in front of a normal eye. Over that journey the focal length of the eye lens:

Q124. A person's eye forms a sharp image of a tree 50 m away, then instantly a sharp image of a phone 30 cm away. What made this possible?

Q125. The image distance in the eye is about 2.3 cm for ALL objects. For a distant object, the eye lens system's focal length must be:

Q126. For a NEARBY object, the eye's focal length must become:

Q127. Assertion: The brain, not the eye alone, is essential for seeing. Reason: The retina sends electrical signals that the brain must interpret into an upright picture.

Q128. A patient's eye lens has become opaque and milky. Which statement is correct?

Q129. Two friends look at the same star. One covers an eye. Compared to before, with one eye they will:

Q130. Why do doctors examine the retina by shining light through the pupil in a DARK room?

Q131. If a person's ciliary muscles are weak and cannot contract properly, they will struggle most with:

Q132. Which of the following does NOT change while the eye adjusts from a bright far scene to a dim near book?

Q133. Case: In a science demo, a bull's-eye lantern shines into a model eye. The model's 'retina' screen is fixed but its gel lens can be squeezed. To focus a CLOSER lantern, the demonstrator should:

Q134. Why is a person normally unaware of their own blind spot?

Q135. Explain the power of accommodation of the human eye. Include what changes, what stays fixed, the role of the ciliary muscles for near and far vision, and why there is a limit expressed as the near point.

Q136. Compare the human eye with a photographic camera, bringing out at least four points of similarity and the one crucial difference in their focusing mechanisms.

Q137. Consider these statements about myopia. I. Distant objects appear blurred. II. The image of a distant object forms in front of the retina. III. It is corrected with a concave lens of negative power. IV. The near point moves further than 25 cm. Which statements are correct?

Q138. An optician's prescription reads −3 D. This tells you the lens is:

Q139. A hypermetropic person's near point is 50 cm. For reading at 25 cm, u and v for the correcting lens are:

Q140. For that case (u = −25, v = −50 cm), the required power is:

Q141. A myopic person's far point is 80 cm. The power of his spectacles is:

Q142. A person wears spectacles of power +3 D. His near point without spectacles (for reading at 25 cm) is at:

Q143. Assertion: A myopic eye has its far point at a finite distance. Reason: The eye's converging power is too high for its length, focusing distant objects before the retina.

Q144. A −0.25 D prescription indicates:

Q145. An old man cannot read at 25 cm, and also cannot see the bus stop across the road. He most likely suffers from:

Q146. Case: A 14-year-old's prescription changed from −1 D to −2 D in two years. This means:

Q147. Why does squinting (partially closing the eyelids) help a myopic person see slightly better?

Q148. The correcting lens for a myopic person forms which kind of image of a distant tree?

Q149. If a hypermetropic eye's near point is at 75 cm, the person CAN clearly see an object at:

Q150. The power of a normal, relaxed human eye is roughly +60 D. This large value is mostly contributed by the:

Q151. For a myopic swimmer who wears −3 D glasses, which statement about reading WITHOUT glasses is correct?

Q152. The near point of a hypermetropic person is 75 cm. Find the power of the lens needed to read at 25 cm.

Q153. Why is a myopic person advised not to use spectacles of higher power than prescribed?

Q154. Explain myopia fully: symptom, the two possible causes, what happens to the far point, and the correction — including why the correcting lens works and how its focal length is chosen. Illustrate with far point = 100 cm.

Q155. Explain hypermetropia fully: symptom, causes, what happens to the near point, and the correction with a worked numerical (near point = 50 cm, reading at 25 cm).

Q156. A 60-year-old teacher uses one pair of spectacles to read books and another to watch cricket on the far field, and finds swapping them all day tiresome. Explain (a) which two defects she has, (b) what physical changes in her eyes caused each, and (c) the single solution an optician would offer, describing its design.

Q157. Derive/justify why the focal length of the correcting lens for a myopic eye equals the negative of the far-point distance, and use it: a person cannot see clearly beyond 4 m. Find the nature, focal length and power of the correction, and state what the world looks like through it.

Q158. Consider these statements about a glass prism. I. Its two refracting faces are inclined to each other. II. The emergent ray is deviated towards the base. III. The emergent ray is parallel to the incident ray. IV. The angle between the refracting faces is the angle of the prism. Which statements are correct?

Q159. A prism splits white light into colours but a rectangular glass slab of the same glass does not, because:

Q160. In the spectrum from a prism, the colours in order from LEAST deviated to MOST deviated are:

Q161. A ray enters a prism and leaves it travelling in a new direction. The angle of deviation is the angle between:

Q162. A prism is drawn with its apex pointing upwards. The emergent ray must slope:

Q163. A raindrop can return sunlight towards the observer, which a glass prism cannot. The step in the drop that makes this possible is:

Q164. A spectrum from one prism is passed into a second, identical prism held inverted. What emerges from the second prism is:

Q165. Dispersion happens in glass but never in vacuum, because in vacuum:

Q166. Violet light deviates more than red because in glass, violet light has:

Q167. A prism produces a spectrum on a screen. If the prism is replaced by one of HIGHER refractive index (same A), the spectrum will be:

Q168. Assertion: Dispersion cannot occur in vacuum. Reason: In vacuum all colours of light travel at the same speed.

Q169. The secondary bow of a double rainbow has reversed colours because light in each drop undergoes:

Q170. A student shines white light through a prism and marks where green lands. If she then shines only YELLOW light at the same angle, its spot will land:

Q171. Case: On a rainy evening, Meera faces east and sees a rainbow. Which statement is correct?

Q172. Why can a lens (like in a projector) show coloured fringes at the edges of images?

Q173. The angle of deviation of a prism is 40° for violet and 37° for red under the same incidence. The angular width of the spectrum between them is:

Q174. In the raindrop, dispersion happens during:

Q175. White light passes through a prism. Just AFTER the first refracting surface (inside the glass), the light is:

Q176. A full-circle rainbow can be seen:

Q177. Which experiment BEST demonstrates that a prism does not add colour to light?

Q178. Sunlight passing through tiny gaps in leaves sometimes shows faint colour fringes on the ground's edge shadows. Water drops hanging on a spider web can show tiny spectra too. Both are examples of:

Q179. Why can a rainbow never be seen at noon with the Sun overhead (from the ground)?

Q180. The spectrum from a prism shows red at the top and violet at the bottom. What does this tell you about the prism's orientation?

Q181. Explain the dispersion of white light by a glass prism. Your answer must cover: what is observed, the order of colours, the cause in terms of speeds and refractive indices, which colours deviate most and least, and why a second inverted prism undoes the effect.

Q182. Explain, step by step, how a rainbow is formed in the sky after rain. Include the three optical processes in each drop, the roles of dispersion and internal reflection, why the observer must stand with the Sun behind, and why different colours come from different drops.

Q183. A student claims: 'Glass creates the colours we see in the spectrum — pure white light has no colours in it.' Design an argument using TWO different experiments to prove the student wrong.

Q184. Consider these statements about twinkling. I. Stars twinkle because the air's refraction keeps changing. II. Planets do not twinkle because they are extended sources. III. Twinkling is strongest near the horizon. IV. Stars would twinkle even when seen from the Moon. Which statements are correct?

Q185. Starlight entering the atmosphere is bent gradually downwards. The eye then places the star higher than it truly is, because the eye:

Q186. Why is the Sun visible for about two minutes before it has actually risen?

Q187. A beam of sunlight through a gap in a curtain becomes visible as a bright shaft in a dusty room. This happens because:

Q188. The visible reddening of the FULL MOON during a lunar eclipse is because sunlight reaching it has:

Q189. Assertion: From a spacecraft, stars do not twinkle. Reason: Twinkling requires a refracting, turbulent atmosphere in the light's path.

Q190. A star's apparent position keeps changing slightly, but a planet's disc stays steady. The KEY difference is the:

Q191. At exactly the moment an observer sees the Sun's disc touch the horizon at sunset, the actual Sun is:

Q192. Mountain-top telescopes are built at high altitude partly because:

Q193. Which change would make sunsets MORE deeply red?

Q194. The size of particles that scatter mainly BLUE light is:

Q195. Case: A driver in dense fog can see the red tail-lights of a truck but not its white number-plate light at the same distance. Why?

Q196. The Tyndall effect is shown by:

Q197. Sunlight filtering through a forest canopy shows visible shafts. The particles responsible are:

Q198. Why does the noon Sun look white/yellowish rather than red?

Q199. If Earth's atmosphere scattered ALL wavelengths equally, the daytime sky would appear:

Q200. Which pair matches phenomenon to cause correctly?