Light is an energy carried in an electromagnetic wave emitted by vibrating electrons in the atoms. 'Light is an electromagnetic radiation that has a wavelength in about the range of 380-780 nm and that may be perceived by the normal unaided human eye'. In simple terms : Light is än electromagnetic radiation, that is visible to the human eye and is within a certain portion of the electromagnetic spectrum. Light is responsible for the sense of sight." Light travels fast and straight at a speed of about 186,000 miles per second [300,000 kilometers per second]. The straight paths of light are called LIGHT RAYS. the 3 ways to obstruct path of light are: To Block Light, Reflect Light, Bend it by changing its path from one medium to another. The chapter Optics Quiz presents important Q&A from the Light & Optics topic.
Optics: Optics is the branch of physics that studies electromagnetic radiation (for example, light and infrared radiation), its interactions with matter, and instruments used to gather information due to these interactions. Optics includes the study of sight. Thus, Optics essentially describes the behavior of visible, ultraviolet, and infrared light. Fact:Light is an electromagnetic wave, and hence other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Light and Optics discusses some basics of the terms involved in the study of Light, an electromagnetic radiation.

Optics Quiz - Important Questions and Answers.
1. When the distance between the object and the plane mirror increases (a) the image remains same (b) the size of the image will become less than the size of the object (c) the distance between the image and the plane mirror increases (d) the distance between the image and the plane mirror decreases Ans:C
2. In lateral inversion (a) right side of the object will be right side of the image. (b) left side of the object will be left side of the image. (c) upside of the object will be down side of the object. (d) right side of the object will be left side of the image. Ans:D
3. The sun is seen before the actual sunrise because of (a) reflection (b) refraction (c) scattering of light (d) rectilinear propagation of light Ans:B
4. Butter paper is an example for ............. object. (a) a transparent (b) a translucent (c) an opaque (d) a luminous Ans:B
5. Power of accommodation of eye implies (a) control intensity (b) prevent internal reflection of light (c) change of focal length of eye lens (d) All of the above Ans:C
6. Which of the following parts of eye protects the eye and gives it shape? (a) Choroid (b) Sclera (c) Yellow spot (d) Ciliary muscles Ans:B
7. The human eye forms the image of an object at its (a) cornea (b) iris (c) pupil (d) retina Ans:D
8. Rainbow is caused due to (a) reflection of sun light from air particles (b) dispersion of sun light from water drops (c) interference of light (d) diffraction of sun rays from water drops Ans:B
9. In the visible spectrum the colour having the shortest wavelength is (a) green (b) red (c) violet (d) blue Ans: C
10. The splitting of white light into seven colours on passing through a glass prism is due to (a) refraction (b) reflection (c) interference (d) diffraction Ans: A
11. At sunrise or at sunset the sun appears to be reddish while at mid-day it looks white. This is because (a) scattering due to dust particles and air molecules causes this phenomenon (b) the sun is cooler at sunrise or at sunset (c) refraction causes this phenomenon (d) diffraction sends red rays to the earth at these times Ans:A
12. A person cannot see objects clearly which are nearer than 75 cm from his eyes, the disease he is suffering from is (a) astigmatism (b) myopia (c) hypermetropia (d) presbyopia Ans:C
13. For seeing a cricket match, we prefer binoculars to the terrestrial telescope, because (a) binoculars give three-dimensional view (b) terrestrial telescope gives inverted image (c) to avoid chromatic aberration (d) to have larger magnification Ans:A
14. Dispersion is the term used to describe (a) the propagation of light in straight lines (b) the splitting of a beam of light into component colours (c) the bending of a beam of light when it strikes a mirror (d) the change that takes place in white light after passage through red glass Ans:B
15. Consider telecommunication through optical fibres. Which of the following statement is not true? (a) Optical fibres can be of graded refractive index (b) Optical fibres have extremely low transmission loss (c) Optical fibres are subject to electromagnetic interference from outside (d) Optical fibres may have homogeneous core with a suitable cladding Ans:C
16. An optician while testing the eyes finds the vision of a patient to be 6/12. By this he means that (a) the person can read the letters of 6 inches from a distance of 12 m (b) the person can read the letters of 12 inches from 6 m (c) the person can read the letters of 6 m which the normal eye can read from 12 m (d) the focal length of eye lens had become half that of the normal eye Ans:C
17. A mirage occurs because (a) the refractive index of atmosphere increases with height (b) the refractive index of atmosphere decreases with height (c) the hot ground acts like a mirror (d) refractive index remains constant with height Ans:A
18. A well cut diamond appears bright because (a) of reflection of light (b) of dispersion of light (c) of the total internal reflection (d) of refraction of light Ans:C
19. Twinkling of stars is on account of (a) large distance of stars and storms in air (b) small size of stars (c) large size of stars (d) large distance of stars and fluctuations in the density of air Ans:D
20. A coin in a beaker filled with water appears raised. This phenomenon occurs because of the property of (a) reflection of light (b) refraction of light (c) total internal reflection of light (d) interference of light Ans:B
21. A spherical air bubble is embedded in a piece of glass. For a ray of light passing through the bubble, it behaves like a (a) converging lens (b) diverging lens (c) plano-converging lens (d) plano-diverging lens Ans:B
22. ‘The stars seem to be higher on the sky than they actually are’. This can be explained by (a) atmospheric refraction (b) dispersion of light (c) total internal reflection (d) diffraction of light Ans:A
23. Yellow colour light is used as fog light because yellow colour (a) light is most scattered by fog (b) has the longest wavelength among all colours (c) has the longest wavelength among all colours except red and orange but the red colour is already used for brake light and stop light whereas orange colour is avoided due to its similarity with red (d) has the shortest wavelength among all colours Ans:C
24. The mirror used for the head light of a car is (a) spherical concave (b) plane (c) cylindrical (d) parabolic concave Ans:D
25. Soap bubble looks coloured due to (a) dispersion (b) reflection (c) interference (d) Any one of these Ans:C
26. A star is emitting yellow light. If it is accelerated towards earth then to an observer on earth, it will appear (a) shinning yellow (b) gradually changing to violet (c) gradually changing to red (d) unchanged Ans:B
27. What should be refractive index of a transparent medium to be invisible in vacuum? (a) 1 (b) 1 (d) None of these Ans:A
28. When a drop of oil is spread on a water surface, it displays beautiful colours in daylight because of (a) dispersion of light (b) reflection of light (c) polarization of light (d) interference of light Ans:D
29. Smoke emerging from a campfire at the bottom of a hill is being observed by a person at some distance, as shown in the figure. It is evening and the sun has just set behind the hill. Consider regions I and II of the smoke going up the sky (a) region I will be slightly brighter than the hill and region II will be slightly brighter than the sky (b) region I will be slightly darker than the hill and region II will be slightly brighter than the sky (c) region I will be slightly brighter than the hill and region II will be slightly darker than the sky (d) region I will be slightly darker than the hill and region II will be slightly darker than the sky Ans:C
30. The ability of an optical instrument to show the images of two adjacent point objects as separate is called (a) dispersive power (b) magnifying power (c) resolving power (d) None of these Ans:C
31. Total internal reflection can take place only if (a) light goes from optically rarer medium to optically denser medium (b) light goes from optically denser medium to rarer medium (c) the refractive indices of the two media are close to different (d) the refractive indices of the two media are widely different Ans:B
32. The least distance of distinct vision of a normal eye of an adult is (a) 25 m (b) 25 cm (c) 25 mm (d) None of these Ans:B
33. Rear-view mirror used in a vehicle is a (a) concave mirror (b) convex mirror (c) plane mirror (d) None of these Ans:B
34. Magnification produced by a rear view mirror fitted in vehicles (a) is less than one (b) is more than one (c) is equal to one (d) can be more than or less than one depending upon the position of the object in front of it Ans:A
35. A child is standing in front of a magic mirror. She finds the image of her head bigger, the middle portion of her body of the same size and that of the legs smaller. The following is the order of combinations for the magic mirror from the top. (a) Plane, convex and concave (b) Convex, concave and plane (c) Concave, plane and convex (d) Convex, plane and concave Ans:C
36. When a CD (compact disc used in audio and video systems) is seen in sunlight, rainbow like colours are seen. This can be explained on the basis of the phenomenon of (a) reflection and diffraction (b) reflection and transmission (c) diffraction and transmission (d) refraction, diffraction and transmission Ans:D
37. A watch shows times as 3 : 25 when seen through a mirror, time appeared will be (a) 8 : 35 (b) 9 : 35 (c) 7 : 35 (d) 8 : 25 Ans:A
38. The fine powder of a coloured glass is seen as (a) coloured (b) white (c) black (d) that of the glass colour Ans:B
39. For which wavelength of light is our eye most sensitives (a) 3.00 nm (b) 555 nm (c) 200 nm (d) 800 nm Ans:B
40. The acronym for LASER is (a) Light Amplification by Stimulated Emission of Radiation (b) Low Amplitude Stimulated Emission of Radiation (c) Low Amplitude Short Energy Radiation (d) Light Amplification by Short Energy Radiation Ans: A