A convex mirror gives magnification +1/3. The object is moved toward the mirror until magnification becomes +1/2. If focal length is 20 cm, the object displacement magnitude is:
Options

Question

A convex mirror gives magnification +1/3. The object is moved toward the mirror until magnification becomes +1/2. If focal length is 20 cm, the object displacement magnitude is:

G1 Physics · Accepted Answer

For convex mirror magnitude relation u=f(1/m−1). Initially u=20(3−1)=40 cm; finally u=20(2−1)=20 cm. Displacement=20 cm.