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प्रश्न
The diagram below shows a lens as a combination of a glass slab and two prisms.
- Name the lens formed by the combination.
- What is the line XX’ called?
- Complete the path of the incident ray AB after passing through the lens.
- The final emergent ray either meets XX’ at a point or appears to come from a point on XX’. Label it as F. What is this point called?
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उत्तर
- The combination forms a concave lens.
- XX' is known as the principal axis.
- complete diagram is drawn as
- The point F is called a focal point or focus.
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संबंधित प्रश्न
A ray of light incident on a lens parallel to its principal axis, after refraction passes through or appears to come from ______.
Distinguish between a real and a virtual image.
Study the diagram shown in Fig. 5.56
where is the object located?
A ray of light incident at the optical centre of lens, passes undeviated after refraction.
For an object placed at a distance 20 cm in front of a convex lens, the image is at a distance 20 cm behind the lens. The focal length of the convex lens is ______.
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.
Define the term focus of a lens.
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.
How will you differentiate between a convex and a concave lens by looking at a distant object.
Complete the following diagram and state what happens to the ray of light after refraction through the lens.
