A convex lens has 9 cm focal length and a concave lens has -18 cm foca – McqOptions

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1.	A convex lens has 9 cm focal length and a concave lens has -18 cm focal length. The focal length of the combination in contact will be [RPMT 1999]
A.	9 cm
B.	- 18 cm
C.	- 9 cm
D.	18 cm
Answer» E.

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