Light Test

When a ray of light passes from one medium to another obliquely, it—

Image formation in a plane mirror is—

Which mirror gives a real and inverted image of an object?

4. Which type of mirror gives both real and virtual images?

5. Which lens is thick in the middle and thin at the edges?

6. Where is the image formed when an object is placed at the focus of a concave lens?

**7. A concave lens always forms a **

8. A ray of light falling obliquely on a plane mirror reflects at what angle?

The focal length of a plane mirror is—

10. Which mirror is used to read small letters or objects?

12. Which material is not used to make lenses?

11. The real image formed by a concave mirror is—

Which of the following can form a real image?

14. The mathematical expression of the law of refraction is—

15. Which mirror is used in a solar cooker?

16. In which case is the angle of reflection equal to the angle of incidence?

17. Which kind of light is visible to the human eye?

19. The focal length of the eye lens changes due to the action of—

18. A person can see distant or nearby objects clearly by adjusting the focal length of the eye lens. This ability of the eye is called—

20. A defect in which a person cannot see distant objects clearly is—

21. Which defect causes the image to form behind the retina?

22. The device used to examine the eye’s retina is—

23. How many types of main lenses are there?

24. Which of the following is not used to make lenses?

25. How many main focal points does a lens have?

26. Which eye part works like a camera shutter?

27. Which eye part works like a camera film?

28. Which lens is used to correct hypermetropia?

30. A pencil appears bent in water because—

29. Which defect is corrected using a cylindrical lens?

31. When red, blue, and green light mix, which color is formed?

32. Which process is used to identify adulteration in oil using light?

 In which year did Newton first measure the speed of light?

34. Which statement is incorrect?

35. Which is correct regarding lenses?

36. Which of the following is not a primary color of light?

37. What color appears at the top of the rainbow?

39. What color is seen when sunlight reflects off small water droplets?

40. The sea appears blue from a distance due to—

41. A person tries to hit fish in water with a spear but misses. Why?

✅ Answer: Refraction

42. Photometry is the unit/measure of—

43. Which natural phenomenon proves light is a wave?

44. Presbyopia is a vision defect that occurs due to—

45. Sodium vapor lamps are mostly used in street lights because—

46. Rainbow formation depends on—

47. In Einstein’s formula E = mc², what does ‘c’ represent?

49. How do we know an object emits heat?

Which of the following are sources of light?

1.      Solar heat

2.      Light bulb

3.      Burning wood

4.      Firefly

Choose correct answer:

50. The refractive index of a medium is highest when light travels fastest in—

51. Infrared light gives—

53. Sometimes, the Sun is visible a few minutes before it actually rises. Why?

52. If two lenses of different focal lengths are kept touching each other, what will happen?

54. What is white light?

55. Which object does not emit its own light?

56. Why does the sky appear red during sunrise and sunset?

57. What is the function of an optical fiber cable?

58. A lens forms a virtual and erect image. Why?

60. Twinkling of stars is due to—

59. Which wave among the following is mechanical?

61. Which color has the highest wavelength?

62. Which surface reflects light the best?

✅ Answer: A smooth, polished surface
🧠 Explanation: Smooth surfaces (like mirrors) reflect light regularly and clearly.

63. Which of the following is due to refraction?

1. Sun visible after sunset
2. Sun appearing early during sunrise
3. Appearance of stars
4. Appearance of rainbow
5. Twinkling of stars

*64. Assertion (A): Red light is used in danger signals.

Reason (R): Red light scatters the least compared to other colors.**

65. Which light has the highest energy?

66. In which medium does sound travel fastest?

67. When a person enters a dark room from bright sunlight, they can’t see immediately but slowly adjust. Why?

68. A man sees two stars—one twinkles more and the other less. Why?

69. Which type of image is formed by plane mirrors?

70. Retina of the eye forms image—

71. Which part of the eye controls the amount of light entering?

72. Which part of the eye reflects the image in humans?

73. Which part of the eye changes shape to adjust focus?

74. What is the normal near point of a healthy human eye?

75. A person can’t see distant or nearby objects clearly. What is this defect called?

76. A far-sighted person cannot see close objects clearly. Which lens corrects this?

77. Myopia is corrected using—

79. Why does a lens magnify an image?

80. When lens gets blurry and hard with age, it's called—

81. Which lens is used for cataract surgery?

82. Which lens is used to correct presbyopia?

83. What kind of image is formed on the retina or pupil?

84. Match the following pairs –

Column I (Eye defect):
A. Near-sightedness
B. Far-sightedness
C. Weak vision
D. Cataract

Column II (Cure):

1. Concave lens
2. Convex lens
3. Spectacle lens
4. Surgery

Matching:

• A → 1
• B → 2
• C → 3
• D → 4
  ✅ Answer: (b) 1 2 3 4
  🧠 Explanation:
• Near-sightedness (Myopia) → Concave lens
• Far-sightedness (Hypermetropia) → Convex lens
• Weak vision → Spectacles
• Cataract → Surgery

85. Why are sunglasses used by some people in strong light?

86. Which of the following pairs is incorrect?

87. Which lens is used to correct long-sightedness (Hypermetropia)?

88. Myopia is related to—

89. What is Hypermetropia?

90. An old man cannot clearly see distant or nearby objects. This condition is—

91. A person cannot see near and far objects clearly. What is this called?

92. What is a rainbow?

93. What is a telescope used for?

94. Which instrument is used to see microorganisms in a science lab?

95. Which device is used in biology labs to observe tiny organisms?

✅ Answer: (c) Compound microscope
🧠 Explanation: Same as above, used for magnifying tiny biological specimens.

96. Which instrument is used to view distant planets?

97. What is the unit of sound intensity?

98. What type of wave is sound?

99. Why does sound not travel in a vacuum?

100. What type of wave is light?

101. What is sound produced by rubbing two objects called?

102. What is used to remove noise pollution?

103. Who discovered light and electromagnetic waves are same?

104. What causes separation of light into different colors?

105. What is caused due to electric effect of light?

106. Which phenomenon occurs in both light and sound?

107. What is the phenomenon called when sound returns after hitting a surface?

✅ Answer: (c) Echo
🧠 Explanation: An echo is sound reflected back after hitting a surface.

108. Which of the following proves that light travels as a wave?

109. Light has a wave nature similar to –

110. The phenomenon of light bouncing back from a surface is called –

111. The bending of light when it passes from one medium to another is –

112. The sun emits energy at 4 x 10²⁶ joules per second. What is the rate at which mass is
 being lost from the Sun according to Einstein’s formula?Use E = mc²

113. In which medium does light travel the fastest?

114. What is the speed of light in vacuum?

✅ Answer: (d) 3 × 10⁸ m/s
🧠 Explanation: The universally accepted speed of light in vacuum is 3 × 10⁸ m/s.

115. As the temperature of the medium increases, the speed of light –

116. Water, air, and glass: In which does light travel the fastest and slowest?

✅ Answer: (c) Fastest in air, slowest in glass
🧠 Explanation:
Speed order: Air > Water > Glass

117. How much time does light take to travel from the moon to the Earth?

118. How much time does sunlight take to reach Earth?

✅ Answer: (c) 8 minutes
🧠 Explanation: Light from the Sun takes approx. 8 minutes and 20 seconds to reach Earth.

119. What is the speed of light?

✅ Answer: (b) 3 × 10⁸ m/sec
🧠 Explanation: Again, standard value.

120. The appearance of the sun during sunrise and sunset is due to –

121. The sun appears red during sunrise and sunset because –

122. Solar eclipse occurs when –

124. What is light year?

123. A lunar eclipse happens on –

125. How is a rainbow formed?

126. Why does the sky appear blue to us?

127. In a CD, the shining surface displays multiple rainbow colors due to –

127. In a CD, the shining surface displays multiple rainbow colors due to –

128. Mirage is formed due to –

✅ Answer: (b) Refraction of light due to temperature difference
🧠 Explanation: A mirage is an optical illusion caused by refraction in layers of air at different temperatures.

129. Why does a pencil look bent in water?

130. A person with color blindness finds it difficult to distinguish colors due to –

131. What causes the twinkling of stars?

✅ Answer: (b) Refraction of light
🧠 Explanation: Light from stars is refracted through Earth's atmosphere, causing the twinkling effect.

146. Which color of light has the highest energy?

147. When light passes from one medium to another, what changes?

148. The sky appears blue because—

147. When light passes from one medium to another, what changes?

149. What is the reason behind the scattering of light in the atmosphere?

150. After rain, the sky appears clearer due to—

166. Where is the image formed by a convex lens of a real object located?

Where is the image formed by a convex lens of a real object located?

167. Retina in the human eye works like—

168. A person sees nearby objects clearly but distant objects appear blurred. This defect is called—

169. If an object is placed at the center of curvature of a concave mirror,
 what will be the number of images formed?

170. A concave mirror forms an image at 90° angle to the axis and a mirror is placed between 
the object and the image. How many images will be formed?

171. What is the angle between the incident ray and the third reflected ray when two mirrors are placed at 60°?

172. If an object is placed between two plane mirrors placed at 60°, how many images will be formed?

173. Convex lens is used for—

174. The direction of light is determined by—

184. How many colors are there in white light?

185. How many colors are used to make color TV?

186. Which color is most deviated when white light passes through a prism?

187. What are primary colors?

🔹 Q189. What is the process of splitting light into different colors called?

190. Which of the following is not a primary color?

192. Which color combination gives maximum visibility during day and night (like traffic signs)?

193. A material that absorbs all light and appears black is called—

194. Why do yellow street lights appear brighter in fog or rain?

195. Why are yellow tiles used in pedestrian crossings at night?

196. How is colored light produced at night?

197. Which color looks hottest in summer sunlight?

198. How is light reflected?