Teaching BPSC 4.0 बिहार उच्च माध्यमिक शिक्षक भर्ती (PGT) Mock Test Physics Optics Refraction and Reflection
The refractive index of the material of a convex lens is 1.5 and the radii of curvature of its surfaces are 20 and 30 cm. The focal length of the lens is:
1
120 cm
2
60 cm
3
24 cm
4
12 cm
5
None of the above/More than one of the above.