Teaching BPSC बिहार माध्यमिक TGT (9 to 10) शिक्षक भर्ती 4.0 Mock Test Physics Optics Refraction and Reflection
A screen is placed 90 cm from an object. The image is formed by using a convex lens twice on the screen by putting the lens at two different locations separated by 20 cm. The focal length of the lens is approximately equal to
1
21.38 cm
2
30.0 cm
3
35.0 cm
4
More than one of the above
5
None of the above