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प्रश्न
Define the term focal length of a lens.
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उत्तर
The distance from the optical centre O of the lens to its second focal point is called the focal length of the lens.
संबंधित प्रश्न
Which one of the following materials cannot be used to make a lens?
The lens A has a focal length of 25 cm whereas another lens B has a focal length of 60 cm. Giving reason state, which lens has more power: A or B.
Which of the two has a greater power: a lens of short focal length or a lens of large focal length?
How is the power of a lens related to its focal length?
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?
How is the sign (+ or -) of power of a lens related to its divergent or convergent action?
If focal length of a convex lens is 20 cm at what is the power of the lens?
The power of lens depends on the focal length of the lens
Increase in the converging power of eye lens cause ‘hypermetropia'
The focal length of a concave lens is 20 cm. The focal length of a convex lens is 25 cm. These two are placed in contact with each other. What is the power of the combination? Is it diverging, converging or undeviating in nature?
