a convex mirror is placed 20cm behind athin convex lens of 15cm focal length when a small object is placed at a distance og 20cm in front of the lens, the image formed at the same place calculata the focal length of the convex lens?
a convex mirror is placed 20cm behind athin convex lens of 15cm focal length when a small object is placed at a distance og 20cm in front of the lens, the image formed at the same place calculata the focal length of the convex lens?










