Page 151 - NCERT Science Class 10 English Medium

travel in the same direction in all media. It appears that when travelling
obliquely from one medium to another, the direction of propagation of
light in the second medium changes. This phenomenon is known as
refraction of light. Let us understand this phenomenon further by doing
a few activities.

Activity 9.79.7
Activity 9.7
Activity 9.7
Activity
Activity 9.7
n Place a coin at the bottom of a bucket filled with water.
n With your eye to a side above water, try to pick up the coin in one
go. Did you succeed in picking up the coin?
n Repeat the Activity. Why did you not succeed in doing it in one go?
n Ask your friends to do this. Compare your experience with theirs.

Activity 9.89.8
Activity
Activity 9.8
9.8
Activity
Activity 9.8
n Place a large shallow bowl on a Table and put a coin in it.
n Move away slowly from the bowl. Stop when the coin just
disappears from your sight.
n Ask a friend to pour water gently into the bowl without disturbing
the coin.
n Keep looking for the coin from your position. Does the coin becomes
visible again from your position? How could this happen?

The coin becomes visible again on pouring water into the bowl. The
coin appears slightly raised above its actual position due to refraction of
light.

Activity
Activity 9.9
Activity 9.9
Activity 9.9
Activity 9.99.9
n Draw a thick straight line in ink, over a sheet of white paper placed
on a Table.
n Place a glass slab over the line in such a way that one of its edges
makes an angle with the line.
n Look at the portion of the line under the slab from the sides. What
do you observe? Does the line under the glass slab appear to be
bent at the edges?
n Next, place the glass slab such that it is normal to the line. What
do you observe now? Does the part of the line under the glass slab
appear bent?
n Look at the line from the top of the glass slab. Does the part of the
line, beneath the slab, appear to be raised? Why does this happen?

9.3.1 Refraction through a Rectangular Glass Slab

To understand the phenomenon of refraction of light through a glass
slab, let us do an Activity.

146 Science

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