Two lenses have focal lengths `f_(1)` and `f_(2)` and their dispersive powers are `omega_(1)` and `omega_(2)` respectively. They will together form an achromatic combination ifA. `omega_(1)=2omega_(2) and f_(1)=2f_(2)`B. `2omega_(1)=omega_(2) and f_(1)=2f_(2)`C. `omega_(1)=2omega_(2) and f_(1)=-2f_(2)`D. `2omega_(1)=omega_(2) and 2f_(1)=f_(2)`

Two lenses have focal lengths `f_(1)` and `f_(2)` and their dispersive

1.	Two lenses have focal lengths `f_(1)` and `f_(2)` and their dispersive powers are `omega_(1)` and `omega_(2)` respectively. They will together form an achromatic combination ifA. `omega_(1)=2omega_(2) and f_(1)=2f_(2)`B. `2omega_(1)=omega_(2) and f_(1)=2f_(2)`C. `omega_(1)=2omega_(2) and f_(1)=-2f_(2)`D. `2omega_(1)=omega_(2) and 2f_(1)=f_(2)`
Answer» Correct Answer - C (c ) Coordinate of achromatic combination is satisfied, if `omega_(1)/(f_(1))+omega_(2)/(f_(2))=0`

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