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
Draw a ray diagram to show the refraction of light through a glass slab and mark angle of refraction and the lateral shift suffered by the ray of light while passing through the slab.
Draw a ray diagram to show the refraction of a monochromatic ray through a prism when it suffers minimum deviation.
For which colour of white light, is the refractive index of a transparent medium the most?
When a ray of light from air enters a denser medium, it ______.
Glass is transparent in nature. Why does glass powder look opaque? When water is poured over it, it again becomes transparent. Why?
How does the angle of deviation produced by a prism depend on the colour of light used? Which colour of white light is deviated (i) most, (ii) least, by a prism?
In the diagram below, PQ is a ray of light incident on a rectangular glass block.
Copy the diagram and complete the path of the ray of light through the glass block. In your diagram, mark the angle of incidence by letter ‘i’ and the angle of emergence by the letter ‘e’.
After a robbery, if a window has been broken, there will be tiny particles of glass. Some of these will be found at the scene of the crime and some may be caught in the thief’s clothing. If the police can prove that these particles are identical, they have a strong case.
A method of doing this is to suspend the particles of glass in a special liquid. Light of a single colour is thrown through the liquid and the particles viewed through a microscope. The temperature of the liquid is then slowly altered. This alters the speed of light through the liquid (i.e., it alters the refractive index). At one particular temperature, the particles of glass disappear. It this happens at the same temperature for both sets of glass particles, they probably came from the same broken pane of glass.
Complete and copy the diagram to show how light bends when it travels from the liquid to the glass and back to the liquid, If the light slows down in the glass.
A ray of monochromatic light is incident from the air on a glass slab:
(i) Draw a labelled ray diagram showing the change in the path of the ray till it emerges from the glass slab.
(ii) Name the two rays that are parallel to each other.
(iii) Mark the lateral displacement in your diagram.
