Diameter of a plano?convex lens is 6 cm and thickness at the centre is – McqOptions

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1.	Diameter of a plano?convex lens is 6 cm and thickness at the centre is 3 mm. If the speed of light in the material of the lens is 2 \[\times \] 108 m/sec, the focal length of the lens is [CPMT 1989]
A.	15 cm
B.	20 cm
C.	30 cm
D.	10 cm
Answer» D. 10 cm

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