EVENTS CONVENT H. SCHOOL
23/02/2021 Class-8 SLOT-2
SCIENCE
Chapter-16
LIGHT
_______________________________________
Answer:We
cannot see objects in the dark room. But we can see objects outside the room,
in case there is light outside the room. To see an object, we need light which
must reflect from the object to the eyes.
Question
2.Differentiate between regular and diffused reflection. Does diffused
reflection mean the failure of the laws of reflection?
Answer:Following are the differences between a regular reflection and diffused
reflection:
No, diffused reflection is not due to failure of laws of reflection.
(a) Polished
wooden table
(d) Chalk
powder
(b) Cardboard
surface
(e) Marble
floor with water spread over it
(c) Mirror
(f) Piece of
paper.
Answer:
(a) A polished
wooden table will have regular reflection because its surface is smooth.
(b) A chalk
powder will get the diffused reflection because chalk particles are not smooth.
(c) Cardboard
surface has minute irregularities on it, so it will have a diffused reflection.
(d) Marble
stone with water spread over it will have regular reflection if water is stable
but if waves are formed then diffused reflection will take place.
(e) A mirror
will reflect light regularly due to its smooth surface.
(f) A piece of
paper will have irregular reflection due to minute irregularities on it.
(a) A person 1
m in front of a plane 2
(b) If you
touch your ear with right hand in front of a plane mirror it will be seen in
the mirror that your right ear is touched with left, left hand
(c) The size of
the pupil becomes when you see in dim light. large
(d) Night birds
have cones than rods in their eyes. lesser
Question-5 Choose the correct option
in Questions :
1 .Angle of
incidence is equal to the angle of reflection
(a) Always (√)
(b) Sometimes
(c) Under
special conditions
(d) Never.
2.Image formed
by a plane mirror is:
(a) virtual,
behind the mirror and enlarged.
(b) virtual,
behind the mirror and of the same size as the object. (√)
(c) real at the
surface of the mirror and enlarged.
(d) real,
behind the mirror and of the same size as the object.
Answer:
Question 1.What
do you understand by the refraction of light?
Answer:The
deviation (bending) of a ray of light when it passes from one transparent
Medium to another, is called refraction of light.
Answer:The
velocity of light changes and also the direction of movement of light changes.
Question 3.What is refracted ray?
Answer:The ray
of light emerging in the
B. Long Answer Type Questions
Question
4.Where should an object be placed for using a convex lens as magnifying glass?
Answer:Object
should be placed between focus and lens.
Answer:Retina
sends sensations to brain through nerve cells.
Answer:Any
smooth and shining surface can act as a mirror. A mirror is a smooth surface
which is polished from its back and can form the image of the object which is
placed in front of it. The image formed by a mirror is a virtual and erect and
is of the same size as that of the object in front of it.
Question 7.What
is dispersion of light?
Answer:A beam
of white light consists of seven colours. When a beam of white light passes
through a prism, it splits into its seven constituent colours. The splitting of
white light into its seven constituent colours is called dispersion of light.
Rainbow is a natural phenomenon showing dispersion.
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Thank your for your valuable responce.
Mrfarooqui