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प्रश्न
State the condition for the following a lens has both its focal lengths equal .
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उत्तर
If a lens has both its focal length equal medium is same on either side of lens.
संबंधित प्रश्न
What is meant by a power of a lens? Define its SI unit.
What does sign of power (+ve or –ve) indicate?
A convex lens of focal length 25 cm and a concave lens of focal length 10 cm are placed in close contact with one another.
(a) What is the power of this combination?
(b) What is the focal length of this combination?
(c) Is this combination converging or diverging?
Two lenses A and B have focal lengths of +20 cm and, −10 cm, respectively.
(a) What is the nature of lens A and lens B?
(b) What is the power of lens A and lens B?
(c) What is the power of combination if lenses A and B are held close together?
How is the sign (+ or -) of power of a lens related to its divergent or convergent action?
How is accommodation produced?
A stick partly immersed in water appears to be bent. Draw a ray diagram to show the bending of the stick when placed in water and viewed obliquely from above.
A convex lens is of focal length 20 cm. Find its power.
Focal length : metre : : power of lens : _______
When monochromatic red light is used instead of blue light in a convex lens, its focal length will ______.
