# When is linear magnification of a convex lens positive and when is it negative? What should be the corresponding distance of the object from convex le

156 views
in Physics
closed
When is linear magnification of a convex lens positive and when is it negative? What should be the corresponding distance of the object from convex lens of focal length 50 cm?

by (71.8k points)
selected by

Linear magnification of a convex lens, m=("size of image" (h_(2)))/("size of object" (h_(1)))=(v)/(u)
Talking h_(1) as positive, magnification (m) will be positive, when h_(2) is positive, i.e., image is erect and virtual. This happens when object distance (u) from the lens is less than focal length (f =50 cm) of the convex lens.
Again magnification (m) will be negative, when h_(2) is negative, i.e., image is inverted and real. This happens when object distance (u) from the lens is more than the focal length (f =50 cm) of the lens.