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प्रश्न
Define the term focus of a lens.
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उत्तर
The focus of a lens (often called the principal focus) is a specific point on its principal axis where light rays parallel to the axis either converge or appear to originate from after passing through the lens.
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संबंधित प्रश्न
In figure, (a) and (b), F1 and F2 are the two foci of thin lenses and AB is the incident ray. Complete the diagram to show the path of the ray AB after refraction through each lens.
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| (a) |
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| (b) |
Study the diagram shown in Fig. 5.56
what are the two other characteristics of the image?
A ray of light incident parallel to the principal axis of a 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.
Make the correct choices in the following items :
A lens used as a magnifying glass
(i) ls a diverging lens
(ii) Produces a virtual image
(iii) ls placed with the object nearer the lens than the principle focus
How will you differentiate between a convex and a concave lens by looking at a printed page?
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.
