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प्रश्न
State two differences between a convex and a concave lens.
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उत्तर १
| Convex lens | Concave lens | |
| 1. | A convex lens can form both real and virtual images | A concave lens always forms a virtual image |
| 2. | It can form a magnified image. | The image is always diminished in size. |
उत्तर २
1) A convex lens is thicker in the middle, while a concave lens is thinner in the middle.
2) A convex lens converges the light ray falling on it, while a concave lens diverges the light ray falling on it.
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संबंधित प्रश्न
The distance between principal focus and optical centre of the lens is _________.
- diameter
- focal length
- principal axis
- optical centre
Define focal length of a divergent lens.
A real image cannot be obtained on a screen.
Two lenses A and B have power of (i) +2D and (ii) −4D respectively. What is the nature and focal length of each lens?
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 convex lens forms an image of an object equal to the size of the object. Where is the object placed in front of the lens?
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.
Complete the ray diagram to show how the rays pass into and out of the 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 |
