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when a red light through a convex lens is replaced by a light of blue colour ,how will the focal length of the lens changes

when a red light through a convex lens is replaced by a light of blue colour ,how will the focal length of the lens changes
 

Grade:12

1 Answers

Shashwat Garg
13 Points
5 years ago
The refractive index of the material of a lens increases with decrease in wavelength of incident light. So focal length will decrease with decrease in wavelength according to Lens maker’s formula. Thus, when we replace red light with blue light, then due to decrease in wavelength, the focal length of the lens will DECREASE. 

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