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प्रश्न
Name two factors on which the focal length of a lens depends.
उत्तर
Focal length depends on :
(1) Curvature of the lens
(2) Material medium of the lens
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संबंधित प्रश्न
An object is placed at a distance of 30 cm in front of a convex mirror of focal length 15 cm. Write four characteristics of the image formed by the mirror.
If a driver has one convex and one plane rear-view mirror, how would the images in each mirror appear different?
State three characteristics of the image formed by a convex mirror.
The image formed by a spherical mirror is virtual. The mirror will be:
(a) concave
(b) convex
(c) either concave or convex
(d) metallic
Two big mirrors A and B are fitted side by side on a wall. A man is standing at such a distance from the wall that he can see the erect image of his face in both the mirrors. When the man starts walking towards the mirrors, he find that the size of his face in mirror A goes on increasing but that in mirror B remains the same.
(a) mirror A is concave and mirror B is convex
(b) mirror A is plane and mirror B is concave
(c) mirror A is concave and mirror B is plane
(d) mirror A is convex and mirror B is concave
An object is placed at a distance of 100 cm from each of the above lenses A and B. Calculate (i) image distance, and (ii) magnification, in each of the two cases.
A driver uses a convex mirror as a rearview mirror. Explain the reason with the help of a ray diagram.
When the reflecting surface is curved outwards the mirror formed will be ______.
The image formed by a convex mirror is always ______.
Match the following.
| Column I | Column II |
| Convex mirror | Radio telescopes |
| Parabolic mirror | Rear-view mirror |
| Snell’s law | Kaleidoscope |
| Dispersion of light | sin i/sin r =μ |
| Refractive index | Rainbow |
