CBSE – 8th Standard Science

Question Bank – Chapter 16 – Light




Q1.  What is reflection of Light?

Ans. Light is reflected from all surfaces it takes place when light is incident on smooth, polished and regular surfaces.


Q2. What is lateral inversion?

Ans. In an image formed by a mirror the left of the object appears on the right and the right appears on the left. This is known as lateral inversion.


Q 3.  What is dispersion of light?

Ans. Splitting of light into its seven colors is known as dispersion of light. Rainbow is a natural phenomenon showing dispersion.


Q4. What  are known as incident and reflected rays?

Ans. After striking the mirror, the ray of light is reflected in another direction. The light ray, which strikes any surface, is called the incident ray. The ray that comes back from the surface after reflection is known as the reflected ray.


Q5. What is a blind spot in human eye?

Ans. At the junction of the optic nerve and the retina, there are no sensory cells, so no vision is possible at that spot; this is called the blind spot.


Q 6. Differentiate between regular and diffused reflection.

Ans. Regular reflection takes place when light is incident on smooth, polished and regular surfaces. Diffused reflection takes place from rough surfaces all the parallel  rays reflected from  are not parallel, the reflection is known as diffused or irregular reflection.


Q 7. Does diffused reflection mean the failure of the laws of reflection?

Ans.  No, diffused reflection is because of irregularities of rough surface’s reflection.


Q 8. What are luminous objects?

Ans. The objects which emit their own light are known as luminous objects, such as the sun, fire, flame of a candle and an electric lamp.


Q 9. State the laws of reflection.

Ans. Two laws of reflection are

(i) The angle of incidence is equal to the angle of reflection.

(ii) Incident ray, reflected ray and the normal drawn at the point of incidence to the reflecting surface, lie in the same plane.


Q 10. Explain how we can take care of our eyes?

Ans. Take proper diet and food enriched with vitamin A, never look at sun or a powerful light directly. Too little or too much light is bad for eyes. Insufficient light causes eyestrain and headaches. Never rub eyes, washing eyes frequently with clean water can protect our eyes.


Q 11. Name some food rich in vitamin A?

Ans. Raw carrots, broccoli, green vegetables and cod liver oil are rich in vitamin A. Eggs, milk, curd, cheese, butter and yellow fruits as papaya and mango are also rich in vitamin A


Q 12. What causes multiple reflections?

Ans. Reflected light can be reflected again it causes multiple reflection. Two mirrors inclined to each other give multiple images. Beautiful patterns are formed in a kaleidoscope because of multiple reflections.


Q13. What is Braille system?

Ans. Visually challenged persons develop their other senses more sharply to improve their interaction with their environment visually challenged persons can read and write using Braille system.