The dispersive power of crown and flint glasses are 0.02 and 0.04 respectively
PHYSICS · Single correct · CBSE · Physics · Ray Optics and Optical Instruments · Ray Optics and Optical Instruments
Problem
The dispersive power of crown and flint glasses are 0.02 and 0.04 respectively. An achromatic converging lens of focal length 40 cm is made by keeping two lenses, one of crown glass and the other of flint glass, in contact with each other. The focal lengths of the two lenses are:
(a) 20 cm and 40 cm
(b) 20 cm and -40 cm
(c) -20 cm and 40 cm
(d) 10 cm and -20 cm