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An achromatic combination of lenses is t...

An achromatic combination of lenses is to be made by using a convex and a concave lens. The two lenses should have

A

equal powers

B

equal refractive indices

C

equal dispersive powers

D

the product of their powers and dispersive powers equal

Text Solution

Verified by Experts

The correct Answer is:
D
The condition for achromatic combination of two lenses is `(f_(1))/(f_(2))=((omega_(1))/(omega_(2)))` numerically.
But power `P=(1)/(f)`
The condition becomes `|(P_(2))/(P_(1))|=|(omega_(1))/(omega_(2))|`
or `omega_(1)P_(1)=omega_(2)P_(2)`
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