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प्रश्न
What type of lenses are used in spectacles worn by an old lady for knitting?
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
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) |
A ray of light incident on a lens parallel to its principal axis, after refraction passes through or appears to come from ______.
In the diagram below, XX’ represents the principal axis, O the optical centre and F the focus of the lens. Complete the path of rays A and B as they emerge out of the lens.
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| (a) | (b) |
Study the diagram shown in Fig. 5.56
where is the object located?
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 ______.
Make the correct choices in the following items:
lf the image can be focused on a screen it must be
A lens forms the image of an object placed at a distance of 45 cm from it on a screen placed at a distance 90 cm on the other side of it. Name the kind of lens.
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.
