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प्रश्न
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उत्तर
Focal length is the distance measured from the optical centre to the focus. The symbol for it is f.
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संबंधित प्रश्न
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?

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 Fig. 5.56
what are the two other characteristics of the image?

The diagram given below shows the position of an object OA in relation to a converging lens L whose foci are at F1 and F2.

- Draw two rays to locate the position of the image.
- State the position of the image with reference to the lens.
- Describe three characteristics of the image.
- Describe how the distance of the image from the lens and its size change as the object is moved towards F1.
A ray of light incident parallel to the principal axis of a lens, passes undeviated after refraction.
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 rrect choices in the following items :
An object is placed 50 cm from a connverging lens of focal length 30 cm. The image produced would be
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.

