Refraction of light
REFRACTION OF LIGHT
Q1. Fill in the blanks
1.
The phenomenon of splitting of light into its component colours
is ____________ (dispersion)
2.
Very fine particles mainly scatter ___________ light. (blue)
3.
The phenomenon of change in the
___________ of light when it passes from one transparent medium to another is
refraction. (direction)
4.
The refractive index depends
upon the ___________ of propagation of light in different media. (relative speed)
Q2.
Answer the followings.
1) What
do you mean by dispersion? Name the different colours of light in the proper
sequence in the spectrum of light
Ans. The phenomenon of splitting of white light into its
component colours is dispersion. The various colours in the spectrum of light are
in the sequence: Violet, indigo, Blue, Green, Yellow, Orange and Red.
2)
Explain
how the formation of rainbow occurs
Ans. 1) The beautiful phenomenon of the rainbow is a combination of
different phenomena – dispersion, refraction and reflection of light.
2. The rainbow appears in the sky after a rain shower.
3. The water droplets act as small prisms.
4.
When sunlight enters the water droplets present in the
atmosphere, they refract and disperse the incident sunlight.
5. Then they reflect it internally inside the droplet
and finally again refract it.
6.
As a collective effect of all
these phenomena, the seven colored rainbow is observed.
3) What
is refraction of light? How is it related to refractive index?
i) The phenomenon of
change in the direction of light when it passes from one transparent medium to
another is called refraction of light.
ii) The extent of change in the direction of the
light ray is different for different media and it is related to the refractive
index of the medium
Q3) Write short
notes on
1) Refraction
observed in the atmosphere
1)
In the atmosphere, there are
different layers of air with different refractive indices which keep on
changing as the physical conditions of air are not stationary (still).
2)
When we observe any object through
this air, the light coming from them refract randomly due to which the apparent
position of the object fluctuates.
3)
The large scale effect of this
phenomenon is the twinkling of stars, advanced sunrise and delayed sunset.
4)
Due to change in the refractive
index of atmosphere, the intensity of light that reaches our eyes from the
stars varies and hence the stars appear twinkling at night.
5)
Advanced sunrise occurs as a ray of
light from the sun enters the earths atmosphere; it follows a curved path due
to refraction before reaching to the observer.
2) Dispersion
of light
1) The
phenomenon of splitting of light into its component colours is dispersion of
light
2) The band
of coloured components of a light beam is called its spectrum
3) When White light is dispersed
into seven colours by a prism, different colours of light bend through
different angles with respect to incident ray.
4) Out of these seven colours, red
light bend the least while violet light bends the most
5) So the rays of each colour emerge
along different paths and become distinct
6) Hence we get a spectrum of seven
different colours in the sequence, Violet, Indigo, Blue, Green, Yellow, Orange
and Red
Nice
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