NCERT Class 8 Science Chapter 16 Light Extra Questions and Answers
Class 8 Science Chapter 16 Extra Questions and Answers – Light. Here in this Page Class VIII Students can Learn Extra Questions & Answer 16th Chapter Science fully Inside.
We Provided Here Light Science Chapter 16 Long Answer Type Question, Very Short Type Questions (VSA) / MCQ Type Questions, Short Type Questions (SA).
1) Fill in the blanks:
a) The most comfortable distance at which one can read with normal eye is about ___ cm. (25)
b) Moon is an____ object. (Illuminated)
c) ____ is a natural phenomenon showing dispersion. (Rainbow)
d) ____cells of retina, Sense color. (Cones)
2) Multiple choice questions:
a) Images are formed by ____ reflection?
a) Diffused b) Regular
Ans. b) Regular
b) The angle of incidence is always ____ the angle of reflection?
a) Less than b) Greater than c) Equal to
Ans. c) Equal to
c) Sun is a ____ object?
a) Illuminated b) Luminous
Ans. b) Luminous
d) ____part of an eye gives it its distinctive color?
a) Cornea b) Pupil c) Iris
Ans. c) Iris
3) Answer the following question:
a) What are incident ray and reflected ray?
Ans. The light ray, which strikes any surface, is called incident ray.
The ray that comes back from the surface after reflection is known as reflected ray.
b) What are angle of incidence and angle of angle of reflection?
Ans. The angle between the normal and the incident ray is called angle of incidence.
The angle between the normal and the reflected ray is called angle of reflection.
c) What are luminous objects? Give an example.
Ans. The objects which emit their own light are known as luminous objects. Example – Torch.
d) What are illuminated objects? Give an example.
Ans. The objects which shine in the light of the other objects are called illuminated objects. Example – Moon.
e) How long an impression of an image on the retina persists for? When does the eye perceive an object as moving?
Ans. An impression of an image persists on the retina for about 1/16th of a second.
If still images of a moving object are flashed on the eye at a rate faster than 16 per second, then the eye perceives this object as moving.
4) Mark your answer as per the codes provide below:
a) A: No vision is possible at the junction of the optic nerve and the retina.
R: At the junction of the optic nerve and the retina, there are no sensory cells.
I.) Both A and R are true and R is the correct explanation of A.
II.) Both A and R are true but R is not the correct explanation of A.
III.) A is true but R is false.
IV.) A is false but R is true.
V.) Both A and R are false.
Ans. I. Both A and R are true and R is the correct explanation of A.
b) A: Too little or too much light is bad for eyes.
R: Insufficient light causes eyestrain and headaches.
I.) Both A and R are true and R is the correct explanation of A.
II.) Both A and R are true but R is not the correct explanation of A.
III.) A is true but R is false.
IV.) A is false but R is true.
Both A and R are false.
Ans. I. Both A and R are true and R is the correct explanation of A.
5) The eye has a roughly spherical shape. The outer coat of the eye is white. It is tough so that it can protect the interior of the eye from accidents. Its transparent front part is called cornea. Behind the cornea, we find a dark muscular structure called iris. In the iris, there is a small opening called the pupil. The size of the pupil is controlled by the iris. The iris is that part of eye which gives it its distinctive color. When we say that a person has green eyes, we refer actually to the color of the iris. The iris controls the amount of light entering into the eye.
a) We find a dark muscular structure called _____.(Iris)
b) The size of the _____ is controlled by the iris.(Pupil)
c) The _____ controls the amount of light entering into the eye. (Iris)
More extra Questions & Answers
1] fill in the blanks
1] the ray that strikes any surface is called incident ray.
2) As per the law of reflection, angle of incidence is always equal angle of reflection.
3)An image in which the left of the object appears on the right and right of the object appears at the left is called lateral inversion.
4)Reflection from a smooth surface like of a mirror is called as regular reflection.
5] splitting of light into its colours is called as dispersion.
6)Sensations failed by the nerve cells are transmitted to the brain through the optic nerve.
7] the size of the pupil is controlled by iris.
Q.2) Say whether the following statement are true or false.
1)Behind the pupil of the eye is a lens which is thicker in the centre.
True
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2)The most comfortable distance at which one can read with a normal eye is about 21 cm .
False
3) Visually impaired person can read and write using the braille system.
True
4)As per the law of reflection, the angle of reflection is equal to angle of reflection.
True
Q.3) Name the following
1) Splitting Of light into its colours
Ans.Dispersion
2) System for visually impaired person to read and write
Ans.Braille system
3)Dark muscular structure behind cornea
Ans.Iris
Q.4) Definition
1) Blind spot
Ans.At the junction of optic nerve and retina,there are no sensory cells,so no vision is possible at spot.This is called blind spot.
2) Angle of incidence
Ans.The angle between the normal and incident ray is called
The angle of incidence.
3) Reflected ray
Ans.The ray that comes back from the surface after reflection is known as reflected ray.
4) Diffused reflection
Ans. When all the parallel rays reflected from a rough or irregular surface are not parallel, the reflection is known as diffused reflection.
Q.5) Answer the following
1) State the laws of reflection.
Ans.a)As per the law of reflection, Angle of incidence is always equal to the angle of reflection.
b)As per the law,the incident ray,the normal at the point of incidence and the reflected ray all lie in the same plane.
2) Explain Braille system .
Ans. Braille system is a popular resource for visually challenged persons. The system was adopted in 1932 by Louis Braille. Visually impaired people learn the Braille system by beginning with letters, then special characters and letter combinations. Braille system has 63 dot pattern where each character represents a letter, a combination of letter, a common word or a grammatical sign. these patterns are embossed to recognise words by touching.
3] what precautions should be taken for the eye care?
Ans. the following precautions need to be taken for I care
I] do not look at the sun or a powerful light directly.
II] always read at normal distance for vision.Do not read by bringing the book too close to your eyes or keeping it too far.
I I I] never rub your eyes. If particles of dust go into your eyes wash your eyes with clean water immediately.
I V] do not use too much light like that of a sun,lamp or a laser light can injure the retina.
V) Use suitable spectacles, if advised.
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