9. Optical density
Light slows down when it enters an optically
denser medium. The refracted ray bends
towards the normal when the second medium
is optically more dense than the first.
10. Light speeds up when it enters an optically
less dense medium. The refracted ray bends
away from the normal when the second
medium is optically less dense than the first.
11. Among the 3 transparent mediums
(air, water and glass), glass has the
highest optical density.
12. LAWS OF REFRACTION
The incident ray, the refracted ray and
the normal at the point of incidence all
lie in the same plane.
13. For two given media,
the ratio sin i ÷ sin r
is a constant, where i
is the angle of
incidence and r is
the angle of
refraction light.
Refractive sin i
Index,n sin r
14. Refractive index
The higher the optical density, the
greater the refractive index. The greater the
refractive index, the greater the bending of
light towards the normal.
15. n = sin i /sin r n = sin r /sin i
When light travels from
a less dense medium to
a denser medium…
When light travels from
a denser medium to a
less dense medium…
16. Other ways of calculating the
refractive index…
Refractive index,
n = real depth/apparent
depth
Refractive index,n=Speed of light in vacuum or air /Speed of
light in medium = c /v
17. The critical angle is the angle of incidence in
the optically denser medium for which the
angle of refraction is 90°.
When,
i = critical angle,c
r = 90°.
18. TOTAL Internal reflection
When i > critical angle, the ray gets
reflected internally. This is called TOTAL
INTERNAL REFLECTION .
19. The light ray must travel from an optically
denser medium towards a less dense one.
The angle of incidence must be
greater than the critical angle.
i
20. We know that
when light travels
from a less dense
medium to a denser
medium.
We know that
when light travels
from a denser
medium to a less
dense medium
Refractive sin r
Index, n sin i
Refractive sin i
Index, n sin r