Geometrical OpticsHard
Question
Two lenses in contact made of materials with dispersive powers in the ratio 2 : 1, behaves as an achromatic diverging focal length 10 cm. The individual focal length of the lenses are :
Options
A.5 cm, - 10 cm
B.- 5 cm, 10 cm
C.10 cm, -20 cm
D.- 20 cm, 10 cm
Solution
= 0 (condition for a chromaticism)ω1 : ω2 = 2 : 1(Given)
⇒ f1 : f2 = - 2 : 1.................. (i) (for fullfill condition)
by (i) & (ii) f1 = - 10 cm & f2 = - 5 cm
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