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?

When is linear magnification of a convex lens positive and when is it

1.	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?
Answer» Solution :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 lessthan 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.