Q. Two lenses of focal lengths +10 cm and -15 cm are put in contact to form an achromatic combination. The ratio of their dispersive power is:

2218 259 Ray Optics and Optical Instruments Report Error

A

+3/2

50%

B

-3/2

25%

C

+2/3

25%

D

-2/3

0%

Solution:

$\frac{ω _{1}}{ω _{2}} = - \frac{f _{1}}{f _{2}}$