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Why does a light ray incident on a rectangular glass slab immersed in any medium emerges parallel to itself? Explain using a diagram
Answer
When a light ray enters a glass slab,
it enters from air(rarer medium) to glass(denser medium).
As light travels from rarer to denser medium,
the ray of light moves towards the normal
When the ray of light reaches the end of the glass slab,
it emerges from glass(denser medium) to air(rarer medium).
As light travels from denser to rarer medium,
the ray of light moves away from the normal
The ray of light emerges parallel to itself because
the bending of the ray of light on top face AB (air-glass interface)
is equal and opposite to
the bending of the ray of light on bottom face CD (glass-air interface)
So, the ray of light emerges parallel to itself
Refractive index of diamond with respect to glass is 1.6 and absolute refractive index of glass is 1.5. Find out the absolute refractive index of diamond.
Answer
Given,
Refractive index of diamond with respect to glass = 1.6
Refractive index of glass =1.5
We have to find the Refractive Index of diamond
Now,
Refractive index of diamond w.r.t glass = Refractive Index of Diamond/Refractive Index of Glass
1.6 = Refractive Index of Diamond/1.5
1.6 × 1.5 = Refractive Index of Diamond
Refractive Index of Diamond = 1.6 × 1.5
= (16/ 10) × (15/10)
= 240 / 100
= 2.4
Therefore, Refractive index of diamond is 2.4.
Draw a ray diagram showing the path of rays of light when it enters with oblique incidence
- from air into water;
- from water into air
Answer
(i) from air into water
When a ray of light travels from air to water
It travels from rarer medium (air) to denser medium (water)
Hence the ray of light bends towards the normal as it enters water.
Therefore,
Angle of refraction < Angle of incidence
(ii) from water into air
When a ray of light travels from water to air
It travels from denser medium (water) to rarer medium (air)
Hence the ray of light bends away from the normal as it enters air.
Therefore,
Angle of refraction < Angle of incidence
A concave mirror produces three times magnified (enlarged) real image of an object placed 10cm in front of it. Where is image located?
Answer
Which phenomenon occurs when light falls on
(a) highly polished surface
(b) a transparent medium
Answer
(a) highly polished surface
When a ray of light falls on a highly polished surface, reflection of light takes place.
(b) a transparent medium
When a ray of light falls on a transparent medium, refraction of light takes place.
