Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact – McqOptions

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1.	Two thin lenses of focal lengths 20 cm and 25 cm are placed in contact convex. The effective power of the combination is [CBSE PMT 1990; RPMT 2001]
A.	45 dioptres
B.	9 dioptres
C.	1/9 dioptre
D.	6 dioptres
Answer» C. 1/9 dioptre

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