6. Refraction of light 01.
Refraction of light:
1) Light changes its direction when going from one transparent medium to
another transparent medium. This is called the refraction of light.
2) medium :
i) denser medium : ((ang i > ang r))
If the refracted ray bends towards the normal, then second medium is denser
medium. i.e ang i > ang r
ii) rarer medium : (ang r > ang r)
If the refracted ray bends away from the normal, then second medium is rarer
medium. i.e ang r > ang i
3) Speed of light :
Speed of light ray in rarer medium is greater than speed of light in denser
medium.
Due to this, light ray bends while traveling from one to other medium.
When light ray is incident perpendicular to surface of medium then it passes
undeviated.
i rare
i denser
r denser r rare
towards the normal. away from the normal.
i rare
r denser
When a light ray is incident normally at the
and hence does not get refracted.
, 02.
Refraction of light passing through a glass slab:
ABCD is a glass slab.
Light rays are incident on glass slab at an angle of incident i.
Since light travels from rarer to denser medium & it bends towards normal (NN')
This refracted ray is now incident on opposite side CD at an angle r.
Since light is travels from denser to rarer medium. So it bends away from
normal.(MM')
The emergent ray is comming out of glass slab is found to be parallel to
incident ray.
So ang e = ang i.
i N
air (rarer)
A O B
N'
r
M
glasss (denser)
O'
D C
e
M'
Laws of refraction:
1) Incident ray and refracted ray at the point of incidence are on the opposite
sides of the normal.
2) the three - incident ray, refracted ray and the normal, are in the same plane.
3) Snells law:
For a given pair of media, & For light of given colour , the ratio of sin i to sin r is
a constant.
Here, ang i => the angle of incidence and ang r => the angle of refraction.
Refraction of light:
1) Light changes its direction when going from one transparent medium to
another transparent medium. This is called the refraction of light.
2) medium :
i) denser medium : ((ang i > ang r))
If the refracted ray bends towards the normal, then second medium is denser
medium. i.e ang i > ang r
ii) rarer medium : (ang r > ang r)
If the refracted ray bends away from the normal, then second medium is rarer
medium. i.e ang r > ang i
3) Speed of light :
Speed of light ray in rarer medium is greater than speed of light in denser
medium.
Due to this, light ray bends while traveling from one to other medium.
When light ray is incident perpendicular to surface of medium then it passes
undeviated.
i rare
i denser
r denser r rare
towards the normal. away from the normal.
i rare
r denser
When a light ray is incident normally at the
and hence does not get refracted.
, 02.
Refraction of light passing through a glass slab:
ABCD is a glass slab.
Light rays are incident on glass slab at an angle of incident i.
Since light travels from rarer to denser medium & it bends towards normal (NN')
This refracted ray is now incident on opposite side CD at an angle r.
Since light is travels from denser to rarer medium. So it bends away from
normal.(MM')
The emergent ray is comming out of glass slab is found to be parallel to
incident ray.
So ang e = ang i.
i N
air (rarer)
A O B
N'
r
M
glasss (denser)
O'
D C
e
M'
Laws of refraction:
1) Incident ray and refracted ray at the point of incidence are on the opposite
sides of the normal.
2) the three - incident ray, refracted ray and the normal, are in the same plane.
3) Snells law:
For a given pair of media, & For light of given colour , the ratio of sin i to sin r is
a constant.
Here, ang i => the angle of incidence and ang r => the angle of refraction.
