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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.
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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
A wall reflects light and a mirror also reflects light. What difference is three in the way they reflect light?
A boy with a mouth 5 cm wide stands 2 m away from a plane mirror. Where is his image and how wide is the image of his mouth?
An extended object in the form of an arrow pointing upward has been placed in front of a plane mirror. Draw a labelled ray-diagram to show the formation of its image.
Explain why, though both a plane mirror and a sheet of paper reflect light but we can see the image of our face in a plane mirror but not in a sheet of paper.
The image of an object formed by a plane mirror is:
(a) virtual
(b) real
(c) diminished
(d) upside-down
Explain how to read the following message which was found on some blotting paper:
A ray of light goes from water into air. Will it bend towards the normal or away from the normal?
State two effects caused by the refraction of light.
When a ray of light passes from air into glass, is the angle of refraction greater than or less than the angle of incidence?
State whether the following statement is true or false:
Refraction occurs because light slows down in denser materials.
What is meant by 'refraction of light'? Draw a labelled ray diagram to show the refraction of light.
What is meant by the 'angle of incidence' and the 'angle of refraction' for a ray of light?
When a light ray passes from air into glass, what happens to its speed? Draw a diagram to show which way the ray of light bends.
Name the phenomenon due to which a pencil partly immersed in water and held obliquely appears to be bent at the water surface.
A vertical ray of light strikes the horizontal surface of some water:
What is the angle of refraction?
Water is optically denser than glass.
Image is formed by a mirror due to refraction of light.
Water is optically .......... than air.
Air is optically .......... than glass.
When a ray of light travels from water to air, it bends ............. the normal.
Draw suitable diagrams to illustrate how a beam of light incident parallel to the principal axis is reflected by:
(a) a concave mirror, and (b) a convex mirror
The diagram (figure) given below shows two parallel rays 1 and 2 incident on (a) a concave mirror, (b) a convex mirror. Draw the reflected rays and mark the focus by the symbol F.
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?
A small air bubble in a glass block when seen from above appears to be raised because of ______.
We can see the sun even when it is little below the horizon because of ______.
List in proper sequence the steps of the experiment for determining the approximate focal length of a given concave mirror by obtaining the image of a distant object.
The laws of reflection hold true for ______.
Due to _______ pencil looks bent in water, in the given experiment.
The incident rays and refracting rays are on opposite sides of the normal.
The speed of light varies in different media.
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.
Assertion and reasoning type
- Assertion: If the refractive index of the medium is high (denser medium) the velocity of the light in that medium will be small
- Reason: Refractive index of the medium is inversely proportional to the velocity of the light
The angle of incidence for a ray of light having zero reflection angle is ______.
A pencil when dipped in water in a glass tumbler appears to be bent at the interface of air and water. Will the pencil appear to be bent to the same extent, if instead of water we use liquids like, kerosene or turpentine. Support your answer with reason.
Light bends as it passes from one medium to another. What is this phenomenon called?
Mirage is an example of refraction and the total internal reflection of light.
Twinkling of stars and Mirage are the two phenomena occurring due to refraction.
How do twinkling stars occur? (or) what is the cause of the twinkling of stars?
The bottom of swimming pool appears to be less deep than the actual one because of
In refraction of light through a glass slab, the directions of the incident ray and the refracted ray are ______.
A ray of light starting from diamond is incident on the interface separating diamond and water. Draw a labelled ray diagram to show. the refraction of light in this case.
When a ray of light travels normal to the given surface, then the angle of refraction is ______.
