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प्रश्न
What type of lenses are used in spectacles worn by an old lady for knitting?
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उत्तर
A converging lens of suitable focal length is used in the spectacles worn by an old lady for knitting.
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संबंधित प्रश्न
Explain optical centre of a lens with the help of proper diagram(s).
State the condition when a lens is called an equi-convex or equi-concave.
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?
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) |
Study the diagram shown in Fig. 5.56
Complete the diagram to show the formation of image A’B’ of the object AB of same size.
State the condition of the following:
A ray passes undeviated through the lens.
(a) Draw a sketch to show how a lens is able to produce an image of the sun on a paper screen.
(b)(i) Would you regard the rays from the sun as being divergent, parallel or convergent?
(ii) What is the name given to the point where such rays meet after they have passed through the lens?
(iii) How does the image of the sun sometimes burn a paper screen?
How will you differentiate between a convex and a concave lens by looking at a distant object.
How will you differentiate between a convex and a concave lens by looking at a printed page?
Mixture of red + blue + green is passed through a convex lens as shown in the diagram below. State whether the ray passes through a single point or through different points on the principal axis after refraction.
