The focal length of double concave lens kept in air with two spherical surfaces of radii R1 = 30 cm and R2 = 60 cm
The focal length of double concave lens kept in air with two spherical surfaces of radii R1 = 30 cm and R2 = 60 cm
A) 40 cm
B) – 40 cm
C) 20 cm
D) – 20 cm
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