1. What is light?
Light is an electromagnetic wave that travels in straight lines.
2. What is reflection of light?
Reflection is the bouncing back of light from a surface.
3. What are the two laws of reflection?
The angle of incidence equals the angle of reflection, and both lie in the same plane with the normal.
4. What is an incident ray?
The ray of light that strikes a reflecting surface.
5. What is a reflected ray?
The ray that bounces off after hitting a surface.
6. What is the normal in reflection?
A line perpendicular to the surface at the point of incidence.
7. What is the angle of incidence?
The angle between the incident ray and the normal.
8. What is the angle of reflection?
The angle between the reflected ray and the normal.
9. What type of reflection occurs on a smooth surface?
Regular reflection produces clear images.
10. What type of reflection occurs on a rough surface?
Diffuse reflection scatters light in all directions.
11. What is a plane mirror?
A flat mirror that reflects light uniformly.
12. What type of image does a plane mirror form?
A virtual, erect, and same-sized image.
13. Why are images in a plane mirror laterally inverted?
Left and right sides swap due to reflection direction.
14. What is the distance of the image in a plane mirror?
It equals the objectâs distance behind the mirror.
15. What happens if the angle of incidence is 0°?
The light reflects back along the same path.
16. What is the minimum number of mirrors for multiple images?
Two mirrors can create multiple images.
17. What is the formula for the number of images in two mirrors?
n
18. How many images form if two mirrors are at 90°?
Three images are formed (360/90 - 1
19. What happens when mirrors are parallel?
Infinite images are formed due to repeated reflections.
20. What is the practical use of a plane mirror?
Itâs used in dressing tables for viewing reflections. ### Spherical Mirrors
21. What is a spherical mirror?
A curved mirror cut from a spherical surface.
22. What is a concave mirror?
A mirror that curves inward and converges light.
23. What is a convex mirror?
A mirror that curves outward and diverges light.
24. What is the center of curvature?
The center of the sphere forming the mirror.
25. What is the radius of curvature?
The distance from the center of curvature to the mirrorâs pole.
26. What is the pole of a mirror?
The central point on the mirrorâs reflecting surface.
27. What is the principal axis?
A line through the pole and center of curvature.
28. What is the principal focus of a concave mirror?
The point where parallel rays converge after reflection.
29. What is the principal focus of a convex mirror?
The point from which parallel rays appear to diverge.
30. What is the focal length of a mirror?
The distance between the pole and the principal focus.
31. How is focal length related to radius of curvature?
Focal length (f) is half the radius of curvature (R/2).
32. What is a real image?
An image formed where light rays actually meet.
33. What is a virtual image?
An image formed where light rays appear to meet.
34. What image does a concave mirror form at infinity?
A real, inverted, and highly diminished image at the focus.
35. What image does a concave mirror form beyond C?
A real, inverted, and diminished image between F and C.
36. What image does a concave mirror form at C?
A real, inverted, and same-sized image at C.
37. What image does a concave mirror form between F and C?
A real, inverted, and magnified image beyond C.
38. What image does a concave mirror form at F?
A real, inverted, and highly magnified image at infinity.
39. What image does a concave mirror form between F and pole?
A virtual, erect, and magnified image behind the mirror.
40. What image does a convex mirror always form?
A virtual, erect, and diminished image behind the mirror.
41. What is the mirror formula?
1/f
42. What is the sign convention for a concave mirror?
Distances left of the pole are negative, right are positive.
43. What is the sign convention for a convex mirror?
Focal length and image distance are negative.
44. What is magnification in mirrors?
The ratio of image height to object height (m
45. How is magnification calculated using distances?
Magnification (m) equals -v/u.
46. What does positive magnification mean?
It indicates a virtual and erect image.
47. What does negative magnification mean?
It indicates a real and inverted image.
48. What is the magnification of a plane mirror?
It is +1, indicating same size and erect image.
49. What is the use of a concave mirror in headlights?
It focuses light into a strong beam.
50. What is the use of a convex mirror in vehicles?
It provides a wide field of view as a rear-view mirror.
51. What happens if an object is at the pole of a concave mirror?
No clear image forms; it overlaps with the object.
52. What is the aperture of a spherical mirror?
The diameter of the mirrorâs reflecting surface.
53. What is a ray diagram for mirrors?
A sketch showing the path of light rays to locate images.
54. How many rays are needed to draw a ray diagram?
Two rays are sufficient to find the image position.
55. What is the principal ray in a concave mirror?
A ray parallel to the axis reflects through the focus.
56. What is the ray through the center of curvature?
It reflects back along the same path.
57. What is the ray through the pole of a mirror?
It reflects symmetrically about the normal.
58. What happens to rays diverging from the focus in a concave mirror?
They reflect parallel to the principal axis.
59. What is the field of view of a convex mirror?
It is wide due to its diverging nature.
60. What is the field of view of a concave mirror?
It is narrow but can magnify objects.
61. What is a reflecting surface?
Any surface that bounces light back, like a mirror.
62. What is a polished surface in reflection?
A smooth surface causing regular reflection.
63. What is the image distance in a convex mirror?
It is always between the pole and focus, negative.
64. What is the object distance in mirrors?
The distance from the pole to the object, usually negative.
65. What happens when light hits a mirror at 45°?
It reflects at 45°, making a 90° angle with the incident ray.
66. What is a periscope?
A device using plane mirrors to see over obstacles.
67. What is a kaleidoscope?
A toy using mirrors to create symmetrical patterns.
68. What is the practical use of multiple reflections?
Itâs used in optical devices like periscopes.
69. What is the speed of light in reflection?
It remains unchanged at 3 à 10⸠m/s in vacuum.
70. What is a shaving mirror?
A concave mirror magnifying the face for shaving.
71. What is a dentistâs mirror?
A small concave mirror to view teeth.
72. What is spherical aberration in mirrors?
Blurring of images due to varying focal points.
73. What is the reflecting side of a concave mirror?
The inner curved surface reflects light.
74. What is the reflecting side of a convex mirror?
The outer curved surface reflects light.
75. What is the magnification when the image is half-sized?
Magnification is 0.5 (diminished image).
76. What is the magnification when the image is doubled?
Magnification is 2 (magnified image).
77. What happens if the object is behind the center of curvature?
A real, diminished image forms between F and C.
78. What is the nature of light in reflection?
Light behaves as rays following geometric rules.
79. What is the focal point in a plane mirror?
It is at infinity as rays donât converge.
80. What is the radius of curvature of a plane mirror?
It is infinite due to no curvature.
81. What is a solar furnace?
A device using concave mirrors to focus sunlight for heat.
82. What is the image in a convex mirror at infinity?
A virtual, highly diminished image at the focus.
83. What is the minimum distance for a clear image in a concave mirror?
The object must be beyond the focus.
84. What is the maximum magnification in a concave mirror?
It occurs when the object is at the focus (infinite).
85. What is the use of mirrors in torches?
Concave mirrors focus light into a beam.
86. What is the angle between incident and reflected rays at 30° incidence?
It is 60° (2 à angle of incidence).
87. What is the image height if magnification is -2?
The image is twice the object height and inverted.
88. What is refraction of light?
The bending of light when passing between media.
89. What causes refraction?
A change in lightâs speed between media causes bending.
90. What is the refractive index?
Itâs the ratio of lightâs speed in vacuum to a medium (n
91. What is Snellâs Law?
nâsinθâ
92. What is the angle of refraction?
The angle between the refracted ray and the normal.
93. What happens when light enters a denser medium?
It slows down and bends toward the normal.
94. What happens when light enters a rarer medium?
It speeds up and bends away from the normal.
95. What is the refractive index of vacuum?
It is 1 as light travels fastest here.
96. What is the refractive index of air?
It is approximately 1, slightly more than vacuum.
97. What is the refractive index of glass?
It is about 1.5, depending on the glass type.
98. What is the refractive index of water?
It is approximately 1.33.
99. What is a denser medium?
A medium with a higher refractive index.
100. What is a rarer medium?
A medium with a lower refractive index.
101. What happens if the angle of incidence is 0° in refraction?
Light passes straight without bending.
102. What is the speed of light in vacuum?
It is 3 à 10⸠meters per second.
103. What happens to light speed in glass?
It slows down to about 2 à 10⸠m/s.
104. What is total internal reflection?
Light reflects fully inside a medium at a critical angle.
105. What is the critical angle?
The angle of incidence where refraction becomes reflection.
106. What condition allows total internal reflection?
Light must travel from a denser to a rarer medium.
107. What is the formula for critical angle?
sinθc
108. What is the critical angle for glass to air?
Itâs about 42° (sinâťÂš(1/1.5)).
109. What is a lens?
A transparent object that refracts light to focus it.
110. What is a convex lens?
A lens thicker at the center that converges light.
111. What is a concave lens?
A lens thinner at the center that diverges light.
112. What is the optical center of a lens?
The central point where light passes without deviation.
113. What is the principal axis of a lens?
A line through the optical center perpendicular to the lens.
114. What is the principal focus of a convex lens?
The point where parallel rays converge after refraction.
115. What is the principal focus of a concave lens?
116. What is the focal length of a lens?
The distance from the optical center to the focus.
117. What is a converging lens?
A convex lens that brings light rays together.
118. What is a diverging lens?
A concave lens that spreads light rays apart.
119. What image does a convex lens form at infinity?
A real, inverted, and diminished image at the focus.
120. What image does a convex lens form beyond 2F?
A real, inverted, and diminished image between F and 2F.
121. What image does a convex lens form at 2F?
A real, inverted, and same-sized image at 2F.
122. What image does a convex lens form between F and 2F?
A real, inverted, and magnified image beyond 2F.
123. What image does a convex lens form at F?
124. What image does a convex lens form between F and lens?
A virtual, erect, and magnified image on the same side.
125. What image does a concave lens form?
A virtual, erect, and diminished image between F and lens.
126. What is the lens formula?
127. What is the sign convention for a convex lens?
Distances to the right are positive, to the left are negative.
128. What is the sign convention for a concave lens?
129. What is magnification in lenses?
130. How is magnification calculated in lenses?
Magnification (m) equals v/u for lenses.
131. What does positive magnification indicate in lenses?
It shows a virtual and erect image.
132. What does negative magnification indicate in lenses?
It shows a real and inverted image.
133. What is the power of a lens?
Itâs the reciprocal of focal length in meters (P
134. What is the unit of lens power?
Diopter (D) measures the power of a lens.
135. What is the power of a convex lens?
It is positive as it converges light.
136. What is the power of a concave lens?
It is negative as it diverges light.
137. What is the power of a 25 cm focal length lens?
Power is +4 D (1/0.25 m).
138. What is the power of a -50 cm focal length lens?
Power is -2 D (1/-0.5 m).
139. What is a prism?
A transparent object with two refracting surfaces at an angle.
140. What is dispersion of light?
The splitting of white light into its colors.
141. Why does dispersion occur in a prism?
Different wavelengths refract at different angles.
142. What is the angle of prism?
The angle between the two refracting surfaces of a prism.
143. What is the angle of deviation in a prism?
The angle by which light bends after passing through.
144. What is a glass slab?
A rectangular block that refracts light without dispersion.
145. What is lateral displacement in a glass slab?
The sideways shift of light after refraction.
146. Why doesnât a glass slab disperse light?
Parallel surfaces recombine the refracted colors.
147. What is the use of a convex lens in a projector?
It forms a real, magnified image on a screen.
148. What is the use of a concave lens in spectacles?
It corrects vision by diverging light rays.
149. What is a ray diagram for lenses?
A sketch showing light paths to locate images.
150. What is the principal ray in a convex lens?
A ray parallel to the axis refracts through the focus.
151. What is the ray through the optical center of a lens?
It passes straight without bending.
152. What is the ray through the focus in a convex lens?
It refracts parallel to the principal axis.
153. What happens to rays diverging from the focus in a concave lens?
They refract parallel to the principal axis.
154. What is the aperture of a lens?
The diameter of the lens collecting light.
155. What is a biconvex lens?
A lens convex on both sides, converging light.
156. What is a biconcave lens?
A lens concave on both sides, diverging light.
157. What is a plano-convex lens?
A lens with one flat and one convex side.
158. What is a plano-concave lens?
A lens with one flat and one concave side.
159. What is chromatic aberration in lenses?
Color fringing due to dispersion of light.
160. What is spherical aberration in lenses?
Blurring due to varying focus across the lens.
161. What is the focal length of a lens combination?
1/F
162. What is the power of combined lenses?
Total power is Pâ + Pâ in diopters.
163. What is the magnification of combined lenses?
Itâs the product of individual magnifications (m
164. What happens when light bends in water?
It appears bent due to refraction at the surface.
165. What is the refractive index of diamond?
It is about 2.42, causing high refraction.
166. What is the effect of a thick lens?
It has a shorter focal length and higher power.
167. What is the effect of a thin lens?
It has a longer focal length and lower power.
168. What is the use of total internal reflection?
Itâs used in optical fibers for communication.
169. What is the critical angle for water to air?
Itâs about 48.6° (sinâťÂš(1/1.33)).
170. What is the wavelength of light?
The distance between two consecutive crests of a wave.
171. What is monochromatic light?
Light of a single wavelength or color.
172. What is polychromatic light?
Light with multiple wavelengths or colors.
173. What is white light?
A mixture of all visible wavelengths.
174. What is the visible spectrum range?
It ranges from 400 nm (violet) to 700 nm (red).
175. Which color has the shortest wavelength?
Violet has the shortest wavelength in the spectrum.
176. Which color has the longest wavelength?
Red has the longest wavelength in the spectrum.
177. What is the frequency of light?
The number of waves passing a point per second.
178. What determines lightâs speed in a medium?
The refractive index determines its speed (v
179. What is a magnifying glass?
A convex lens enlarging objects when held close.
180. What is a camera lens?
A convex lens forming real images on film.
181. What is the bending of a pencil in water?
Refraction makes it appear bent at the surface.
182. What is the use of a prism in experiments?
It disperses light to study its components.
183. What is the base of a prism?
The side opposite the prismâs refracting angle.
184. What is the minimum deviation in a prism?
The smallest angle of deviation for light passing through.
185. What is the effect of prism thickness?
Thicker prisms cause greater deviation of light.
186. What is the refractive index of a prism?
It depends on the prism material, typically 1.5 for glass.
187. What is the path of light in a glass slab?
It bends twice but emerges parallel to the incident ray.
188. What is the thickness of a glass slab?
It affects the lateral displacement of light.
189. What is the use of a convex lens in a telescope?
It magnifies distant objects as an objective lens.
190. What is the use of a concave lens in a telescope?
It corrects aberrations as an eyepiece component.
191. What is the image distance in a convex lens?
It varies with object position, positive for real images.
192. What is the object distance in lenses?
The distance from the lens to the object, usually negative.
193. What is the focal length of a 2 D lens?
It is 50 cm (f
194. What is the focal length of a -4 D lens?
It is -25 cm (f
195. What is the power of a lens with 10 cm focal length?
Power is +10 D (1/0.1 m).
196. What is the power of a lens with -20 cm focal length?
Power is -5 D (1/-0.2 m).
197. What is the magnification of a convex lens at 2F?
It is -1 (same size, inverted).
198. What is the magnification of a concave lens at infinity?
It approaches 0 (highly diminished).
199. What is the effect of lens curvature?
Greater curvature shortens the focal length.
200. What is the refractive index ratio?
Itâs the ratio of two mediaâs refractive indices (nâ/nâ).
201. What is the critical angle significance?
It marks the boundary for total internal reflection.
202. What is the use of refraction in lenses?
It focuses light to form images in optical devices.
203. What is the path of light in a convex lens?
It bends inward to converge at the focus.
204. What is the path of light in a concave lens?
It bends outward, appearing to diverge from the focus.
205. What is the nature of light in refraction?
Light changes direction due to speed variation.
206. What is the angle of incidence in refraction?
207. What is the practical use of a glass slab?
It demonstrates refraction without changing lightâs direction.
208. What is the effect of medium density on refraction?
Denser media cause greater bending toward the normal.
209. What is the refractive index of ice?
It is about 1.31, less than water.
210. What is the refractive index of kerosene?
It is approximately 1.44.
211. What is the power of a lens with infinite focal length?
It is 0 D, as in a flat glass.
212. What is the image in a convex lens at the optical center?
No image forms; it overlaps with the object.
213. What is the use of a lens in a microscope?
Convex lenses magnify tiny objects for viewing.
214. What is the deviation in a thin prism?
Itâs small due to a lesser angle of prism.
215. What is the effect of wavelength on refraction?
Shorter wavelengths refract more than longer ones.
216. What is the practical use of dispersion?
Itâs used in spectrometers to analyze light.
217. What is the magnification when image size equals object size?
Magnification is 1 (same size).
218. What is the power of a plano-convex lens?
It depends on the curved sideâs focal length.
219. What is the critical angle for diamond to air?
Itâs about 24.4° (sinâťÂš(1/2.42)).
220. What is the bending of light in a lens?
It depends on the lens shape and medium.
221. What is the use of refraction in a periscope?
Lenses can enhance viewing with mirrors.
222. What is the image height if magnification is 0.5?
The image is half the object height.
223. What is the focal length of a lens with 1 D power?
It is 1 meter (100 cm).
224. What is the effect of lens thickness on refraction?
Thicker lenses refract light more strongly.
225. What is the practical use of a concave lens?
Itâs used in optical corrections and projectors.
226. What is the refractive index of a lens material?
It determines how much light bends inside it.
227. What is the angle of refraction at the critical angle?
It is 90°, along the boundary surface.
228. What is the image in a concave lens at the focus?
A virtual, diminished image forms closer to the lens.
229. What is the use of a convex lens in a searchlight?
It focuses light into a narrow beam.
230. What is the power of a lens with 33.3 cm focal length?
Power is +3 D (1/0.333 m).
231. What is the magnification of a lens at infinity?
It approaches 0 for convex, remains small for concave.
232. What is the practical use of a prism in optics?
It separates light to study its properties.
233. What is the bending of light in a denser medium?
Light bends more due to slower speed.
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