A student places a small object in front of a thin convex lens

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Geometric Optics · Geometric Optics

Problem

A student places a small object

30\,\text{cm}

in front of a thin convex lens. The real image forms

45\,\text{cm}

on the opposite side of the lens. What is the focal length of the lens, to the nearest whole centimeter? (a)

15\,\text{cm}

(b)

75\,\text{cm}

(c)

18\,\text{cm}

(d)

24\,\text{cm}