Advertisements
Advertisements
Question
The refractive index of glass is 1.5. From a point P inside a glass block, draw rays PA, PB and PC incident on the glass air surface at an angle of incidence 30°, 42° and 60° respectively.
- In the diagram show the approximate direction of these rays as they emerge out of the block.
- What is the angle of refraction for the ray PB?
`("Take" sin 42° =2/3)`
Advertisements
Solution
- A diagram with rays PA, PB and PC is shown below:
- Given, μ = 1.5
As we know,
`sin i_c = 1/mu`
substituting the values in the formula, we get,
`sin i_c = 1/1.5`
sin ic = 0.667
ic = 41.8
Hence, we can round off ic = 42°
Applying `sin r/sin i = ""_amu_g`
sin r = `""_amu_g xx sin i`
sin r = `""_amu_g xx sin 42°`
Given, sin 42° = `2/3`
and `""_amu_g = 3/2`
substituting the value in the formula, we get,
`sin r = 3/2 xx 2/3`
sin r = 1
As sin r = 1, the angle of refraction is 90°.
APPEARS IN
RELATED QUESTIONS
Why is the ratio of the velocities of light of wavelengths 4000Å and 8000Å in vacuum 1: 1?
A ray of light passes from glass into air. The angle of refraction will be:
(a) equal to the angle of incidence
(b) greater than the angle of incidence
(c) smaller than the angle of incidence
(d) 45°
What is the correct reason for blinking / flickering of stars? Explain it.
a) The blasts in the stars.
b) Absorption of star light by the atmosphere.
c) Motion of the stars.
d) Changing refractive index of gases in the atmosphere.
Draw a diagram to show the splitting of white light into its constituent colours.
In an experiment of finding the refractive index of glass, if blue light is replaced by the red light, how will the refractive index of glass change? Give reason in support of your answer.
A ray of light strikes the surface at a rectangular glass slab such that the angle of incidence is 45o.
In each case, draw diagram to show the path taken by the ray as it passes through the glass slab and emerges from it.
A ray of monochromatic light is incident from air into a glass slab. Draw a labelled ray diagram indicating the change in its path till it emerges out of the slab. In the diagram, mark the angle of incidence (i) and the angle of refraction (r) at the first interface. How is the refractive index of glass related to the angles i and r?
The speed of light in air is 3 × 108 ms-1. Calculate the speed of light in water. The refractive index of water is 4/3.
Draw the ray diagram of a glass slab having medium A and B for the velocity of light ray VA and VB respectively and define Snell's law.
- If VB = 1.5 VA, then which medium is denser?
- What is the refractive index of A with respect to B?
- What is the refractive index of B with respect to A?
