a point object is located at a distance of 30 cm on the principal access of a convex lens of a focal length 20 cm. if the lens is move away from object by 10 cm, find the distance through which the image move?
a point object is located at a distance of 30 cm on the principal access of a convex lens of a focal length 20 cm. if the lens is move away from object by 10 cm, find the distance through which the image move?