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प्रश्न
With the help of a diagram, show how when light falls obliquely on the side of a rectangular glass slab, the emergent ray is parallel to the incident ray.
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उत्तर
In the following figure, a light ray travelling in air is incident on the rectangular glass slab. It gets refracted and bends towards the normal. Again, a change in the direction takes place when the refracted ray travelling in glass emerges into air. Here, the light ray bends away from the normal. We see that the incident and emergent rays are parallel to each other. These rays are parallel because the extent of bending on the opposite and parallel faces of slab is equal and opposite.
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संबंधित प्रश्न
What is meant by 'reflection of light'?
A ray of light goes from water into air. Will it bend towards the normal or away from the normal?
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'? Draw a labelled ray diagram to show the refraction 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.
Light travels at a lower speed in water than in air.
What do you understand by refraction of light?
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.
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.
Choose the correct option from given alternative:
A real image is formed by the light rays after reflection or refraction when they:
(A) actually meet or intersect with each other.
(B) actually converge at a point
(C) appear to meet when they are produced in the backward direction.
(D) appear to diverge from a point.
Which of the above statements are correct?
Write scientific reason.
A pencil appears to be broken near the surface of water.
Numerical problems.
The speed of light in water is 2.25 × 108 ms–1. If the speed of light in vacuum is 3 × 108 ms–1, calculate the refractive index of water.
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 from air to glass at the point O on the hemispherical glass slab is.
Noor, a young student, was trying to demonstrate some properties of light in her Science project work. She kept ‘X’ inside the box (as shown in the figure) and with the help of a laser pointer made light rays pass through the holes on one side of the box. She had a small butter-paper screen to see the spots of light being cast as they emerged.
Her friend noted the following observations from this demonstration:
- Glass is optically rarer than air.
- Air and glass allow light to pass through them with the same velocity.
- Air is optically rarer than glass.
- Speed of light through a denser medium is faster than that of a rarer medium.
- The ratio: sin of angle of incidence in the first medium to the ratio of sin of angle of refraction in the second medium, gives the refractive index of the second material with respect to the first one.
Which one of the combinations of the above statements given below is correct.
Light bends as it passes from one medium to another. What is this phenomenon called?
Light is refracted or bent while going from one medium to another because of its ______ changes.
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.
