Two lenses of focal legths `f_(1) and f_(2)` are kept in contact coaxially. The resultant power of combination willl be

Options

A. `(f_(1)f_(2))/(f_(1) - f_(2))`
B. `(f_(1) + f_(2))/(f_(1)f_(2))`
C. `f_(1) + f_(2)`
D. `(f_(1))/(f_(2)) + (f_(2))/(f_(1))`

Answer

A, B

Explanation

` P = (1)/(f_(1)) + (1)/(f_(2)) = (f_(1) + f_(2))/(f_(1)f_(2))`