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प्रश्न
The distance between principal focus and optical centre of the lens is _________.
- diameter
- focal length
- principal axis
- optical centre
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उत्तर
(b) Focal length
The distance between the principal focus and the optical centre of the lens is its focal length.
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संबंधित प्रश्न
A concave lens always forms a virtual image.
A real image cannot be obtained on a screen.
State two differences between a convex and a concave lens.
A diverging mirror of radius of curvature 40 cm forms an image which is half the height of the object. Find the object and image positions.
Explain why, a stick half immersed in water appears to be bent at the surface. Draw a labelled diagram to illustrate your answer.
Write the new Cartesian sign convention for spherical lenses.
If a spherical lens has a power of, −0.25 D, the focal length of this lens will be :
(a) −4 cm
(b) −400 mm
(c) −4 m
(d) −40 cm
What are the three principal rays that are drawn to construct the ray diagram for the image formed by a lens? Draw diagrams to support your answer.
A lens forms the image of an object placed at a distance 15 cm from it, at a distance 60 cm in front of it. Find the nature of image.
My grandfather uses a bifocal lens in his spectacle. Explain why.
Complete the ray diagram to show how the rays pass into and out of the lens?
Which diagram shows image formation of an object on a screen by a converging lens?
Complete the following table for convex lens:
| Sr. No. | Position of the object | Position of the image | Nature of the image |
| 1. | Beyond 2F1 | __________________ | ________________________ |
| 2. | __________________ | At infinity | ________________________ |
| 3. | __________________ | __________________ | Real, inverted and enlarged |
