A convex mirror with focal length of -20 cm forms an image 12 cm behind the surface.Where is the object located as measured from the surface?

Question

Quizplus · Accepted Answer

Using the mirror equation:
1/f = 1/s + 1/s'
where f is the focal length, s is the object distance, and s' is the image distance (all measured from the mirror surface).

Plugging in the given values:
1/-20 = 1/s + 1/12

Solving for s:
s = -30 cm

Note that the negative sign indicates that the object is located on the opposite side of the mirror as the incident light. The distance is therefore 30 cm from the mirror surface (since the mirror itself has no thickness).

Therefore, the answer is D) 30 cm.

A Convex Mirror with Focal Length of -20 Cm Forms