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प्रश्न
State the condition when a lens is called an equi-convex or equi-concave.
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उत्तर
A lens is called an equiconvex or equiconcave when radii of curvature of the two surfaces of lens are equal.
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संबंधित 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?

A ray of light incident on a lens parallel to its principal axis, after refraction passes through or appears to come from ______.
Study the diagram shown in the following Figure.
Name the lens LL’ and draw its outline.

Study the diagram shown in Fig. 5.56
where is the object located?

State the condition of the following:
A lens has both its focal lengths equal.
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?
What type of lenses are used in spectacles worn by an old lady for knitting?
Name the subjective property of light related to its wavelength.
In the following diagram, L1 and L2 are the two convex lense placed at separation equal to the sum of focal lengths of the two lenses. A and B are the two rays of light incident on the lens L1. Complete the path of rays till they emerge out of the lens L2.

What principles have you used in completing the diagram?
