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When monochromatic red light is used ins...

When monochromatic red light is used instead of blue light in a convex lens, its focal length will ......

A

Does not depend on colour of light

B

increase the squeeze of the lens

C

Decrease

D

Remain same

Text Solution

Verified by Experts

The correct Answer is:
B
Focal length of a lens is given by
`(1)/(f) = (mu-1) ((1)/(R_(1)) - (1)/(R_(2)))`
`(1)/(f) propmu prop(1)/(lambda) implies f prop lambda`
`lambda_(R) gt lambda_(B) implies f_(R) gt f_(B)`
Focal length will increase
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ALLEN -GEOMETRICAL OPTICS-EXERCISE-05 (A)
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  16. To find the focal length of a convex mirror , a student records the fo...

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