Advertisements
Advertisements
प्रश्न
Explain ‘mirage’ as an illustration of refraction.
Advertisements
उत्तर
- On a hot, clear, sunny day, along a level road, there appears a pond of water ahead of the road. However, if we physically reach the spot, there is nothing but the dry road, and the water pond again appears some distance ahead. This illusion is called a mirage.
- Mirages result from the refraction of light through a non-uniform medium.
- On a hot day the air in contact with the road is hottest, and as we go up, it gets gradually cooler. The refractive index of air thus decreases with height. Hot air tends to be less optically dense than cooler air, which results in a non-uniform medium.
- Light travels in a straight line through a uniform medium but refracts when travelling through a non-uniform medium.
- Thus, the ray of light coming from the top of an object gets refracted while travelling downwards into less optically dense air and becomes more and more horizontal, as shown in the figure.
- As it almost touches the road, it bends (refracts) upward. Then onwards, upward bending continues due to denser air.
- As a result, for an observer, it appears to be coming from below, thereby giving an illusion of reflection from an (imaginary) water surface.
APPEARS IN
संबंधित प्रश्न
A ray of light travels from water to air as shown in the diagram given below :
1) Copy the diagram and complete the path of the way. Given the critical angle for water is 48°.
2) State the condition so that internal reflection occurs in the above diagram.
What do you understand by the deviation produced by a prism? Why is it caused?
A light ray does not bend at the boundary in passing from one medium to the other medium if the angle of incident is ______.
Total internal reflection occurs only when a ray of light passes from a ______ medium to a ______ medium.
Calculate the speed of light in a medium whose critical angle is 30° ?
Prove the statement.
A rainbow is the combined effect of the refraction, dispersion, and total internal reflection of light.
Define critical angle for a given medium.
Plot a graph between
Angle of incidence versus angle of reflection,
Plot a graph between
Angle of incidence versus angle of refraction.
State two advantages of using a right-angle prism as a reflector, rather than a plane mirror.
A ray of light is incident on a glass surface at an angle of 50° with the corresponding angle of refraction 30°. Find the value of the R.I. of glass.
Choose the correct option.
Consider the following phenomena/ applications: P) Mirage, Q) rainbow, R) Optical fibre and S) glittering of a diamond. Total internal reflection is involved in
Observe the given figure and write appropriate phenomenon of light in the box.
The resultant `vec"R"` of `vec"P"` and `vec"Q"` is perpendicular to `vec"P"`. Also `|vec"P"|=|vec"R"|`. The angle between `vec"P"` and `vec"Q"` is ______.
[tan 45° = 1]
For the same angle of incidence, the angle of refraction in four media A, B, C and D are 25°, 30°, 35° and 40° respectively. The speed of light is least in medium ______.
Total internal reflection can take place only if light is travelling from ______.
The twinkling effect of star light is due to ______.
The outer concentric shell in optic fiber is called ______.
A bundle of glass threads, each of which is capable of transmitting messages using light waves is called ______.
What is the phenomenon used in optical fiber? Explain.
What are the examples of total internal reflection in nature?
State the condition under which total internal reflection occurs. Give the mathematical expression for total internal reflection.
A Rainbow is a beautiful natural phenomenon formed because of the following:
A given ray of light suffers minimum deviation in an equilateral prism P. Additional prism Q and R of identical shape and of the same material as P are now added as shown in the figure. The ray will now suffer ______.
Find the value of θ in the given figure.
Name any two phenomena which take place in the formation of a rainbow.
