Focal length of two lens are`f`and`f^(')`ans dispersive powers are `omega_(0)`and`2omega_(0)`
Channel: Doubtnut
Date: 2020-08-23

Focal length of two lens are`f`and`f^(')`ans dispersive powers are `omega_(0)`and`2omega_(0)`.To form achromatic combination from these-  (1)`f^(')=2f ,(2) f^(')=-2f` (3)`f^(')=-f//2`