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प्रश्न
Fig. shows two rays of light Op and OQ coming from an object at the bottom of a pond, incident on the water surface.
(a) Mark on the diagram
(i) The angle of incidence of ray OP,
(ii) The angle of refraction of ray Op,
(iii) The position of image of the object as seen from above.
(iv) An approximate path of the ray OQ.
(b) Explain, why do the rays of light change directions on passing from water to air.
(c) A fish in water sees everything outside the water by rays of light entering its eye in a small cone of light. Draw a diagram and explain how does this happen.
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उत्तर
(i) Angle of incidence (i) of ray OP is marked in the above diagram.
(ii) Angle of refraction (r) of ray OP is marked in the above diagram.
(iii) The position of image of the object (O') as seen from above is marked in the diagram.
(iv) An approximate path of ray OQ is shown in the above diagram.
(b) Water is a denser medium as compared to air; so on passing from water (denser) to air (rarer) the speed of light of light increases and it bends away from the normal.
(c)
Refraction is the bending of light as it passes from a medium of one optical density into a medium of a different optical density, as from air to water or water into air. The amount of bending is dependent upon the incident angle of the light. In the diagram below, a light ray, "A" strikes the water at right angles and passes through the surface without bending. But as the incident angle decreases (becomes less than 90 degrees) the light bends more and morerays "B" and "C." Light striking the surface parallel to the surface, bends downward.
Since light is coming into the water from all directions, refraction creates a cone of light with its base on the surface and its apex at the fish's eye. The base of the cone is a circular opening at the surface through which the fish sees the entire outside world. This opening is called the "Fish's Window". Only the light passing through the window enters the fish's eye. Notice line "D," It's a ray entering the water beyond the window; refraction bends it such that it cannot reach the fish's eye.
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संबंधित प्रश्न
In the following figure (a) and (b), F1 and F2 are positions of the two foci of thin lenses. Draw the path taken by the light ray AB after it emerges from each lens.
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| (a) |
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| (b) |
The diagram given below shows the position of an object OA in relation to a converging lens L whose foci are at F1 and F2.
- Draw two rays to locate the position of the image.
- State the position of the image with reference to the lens.
- Describe three characteristics of the image.
- Describe how the distance of the image from the lens and its size change as the object is moved towards F1.
The diagram given below shows the position of an object OA in relation to a converging lens whose foci are at F1 and F2.
Describe three characteristic of the image.
In the following diagram ., the object and the image formed by the respective lenses are shown. Complete the ray diagram, and locate the focus. Find the focal length of the lens.
Make the correct choices in the following items:
lf the image can be focused on a screen it must be
How will you differentiate between a convex and a concave lens by looking at a printed page?
Name the subjective property of light related to its wavelength.
State the nature and position of the object on the principal axis to obtain a real and magnified image.
The diagram showed a lens as a combination of one glass block and two prisms. Complete the ray diagram and show the part of the incident ray AB after passing through the lens.
(i) Name of the lens formed by the combination.
(ii) What is the line XX’ called?
(iii) Mark the focus F.
Complete the following diagram and state what happens to the ray of light after refraction through the lens.
