If the magnitude of dispersive powers of two lenses are 0

Last updated: 6/8/2023

If the magnitude of dispersive powers of two lenses are 0 024 and 0 036 Then their focal lengths will be for aberration free combination 1 30 cm 40 cm 3 10 cm 30 cm 2 30 cm 45 cm 4 20 cm 35 cm