Advertisements
Advertisements
प्रश्न
Explain how the formation of a rainbow occurs.
Explain the phenomenon of rainbow formation in the sky. Draw the labelled ray diagram in support of your explanation.
Advertisements
उत्तर
- The beautiful phenomenon of the rainbow is a combination of different phenomena, such as dispersion, refraction, and reflection of light.
- The rainbow appears in the sky after a rain shower.
- The water droplets act as small prisms.
- When sunlight enters the water droplets present in the atmosphere, they refract and disperse the incident sunlight.
- Then they reflect it internally within the droplet and finally refract it again.
- As a collective effect of all these phenomena, the seven coloured rainbows are observed.
संबंधित प्रश्न
What is refraction of light?
Fill in the following blank with a suitable word:
When light is reflected, the angles of incidence and reflection are ............ .
Write the word AMBULANCE as it would appear when reflected in a plane mirror. Why is it sometimes written in this way (as its mirror image) on the front of an ambulance?
What are the important differences between looking at a photograph of your face and looking at yourself in a plane mirror?
What type of reflection of light takes place from a cinema screen?
The boy walks towards the mirror at a speed of 1 m/s. At what speed does his image approach him?
State the uses of plane mirrors.
The image formed by a plane mirror is :
(a) virtual, behind the mirror and enlarged.
(b) virtual, behind the mirror and of the same size as the object.
(c) real, at the surface of the mirror and enlarged.
(d) real, behind the mirror and of the same size as the object.
The figure given alongside shows the image of a clock as seen in a plane mirror. The correct time is:
A man stands 10 m in front of a large plane mirror. How far must the walk before he is 5 m away from his image?
A man sits in an optician's chair looking into plane mirror which is 2 m away from him and views the image of a chart which faces the mirror and is 50 cm behind his head. How far away from his eyes does the chart appear to be?
Explain how to read the following message which was found on some blotting paper:
State two effects caused by the refraction of light.
In which material do you think light rays travel faster-glass or air?
State whether the following statement is true or false:
Refraction occurs because light slows down in denser materials.
Fill in the following blank with suitable word:
Light bends when is passes from water into air. We say that it is ............
What is meant by ‘refraction of light’?
Name the phenomenon due to which a pencil partly immersed in water and held obliquely appears to be bent at the water surface.
How does the light have to enter the glass:
to produce a large amount of bending?
Water is optically denser than glass.
The depth of a pond when seen from above appears to be less.
What is the cause of refraction of light when it passes from one medium to another?
A light ray suffers reflection and refraction at the boundary in passing from air to water. Draw a neat labelled ray diagram to show it.
A ray of light A incident from air suffers partial reflection and refraction at the boundary of water.
- Complete the diagram showing (i) the reflected ray B and (ii) the refracted ray C.
- How are the angles of incidence i and refraction r related?
List four characteristics of the image formed by a concave lens of focal length 20 cm when the object is placed at a distance of 40 cm from its optical centre.
The size of image of an object by a convex lens of focal length 20 cm is observed to be reduced to `1/3` rd of its size . Find the distance of the object from the optical centre of the lens .
Due to _______ pencil looks bent in water, in the given experiment.
Light changes its direction when going from one transparent medium to another transparent medium. This is called _______.
Identify the wrong figure from the following.
The speed of light varies in different media.
Write scientific reason.
A pencil appears to be broken near the surface of water.
Observe the given figure and name the following.
| Ray AB | |
| Ray NM | |
| Ray MD | |
| ∠ r |
State whether true or false. If false, correct the statement.
The angle of deviation depends on the refractive index of the glass.
In the above diagram light is travelling through different media. It is noted by a scientist that ∠1= ∠3 = ∠4 but ∠2 < ∠1. Which of the following statement would be correct?
How does the light travel?
Light bends as it passes from one medium to another. What is this phenomenon called?
Light travels fastest in a vacuum. Why?
The bending of light as it passes from one medium to another is called ______.
Match the following:
| Column I | Column II | ||
| 1. | r > 90 | a. | Light gazes at the surface of separation between the two modes. |
| 2. | r = 90 | b. | No refraction. |
| 3. | r < 90 | c. | Refracted ray away from the normal |
