An object is placed in front of a concave spherical mirror

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

Problem

An object is placed

30\,\text{cm}

in front of a concave spherical mirror. The real image is found

45\,\text{cm}

in front of the mirror. What is the focal length of the mirror? (a)

20\,\text{cm}

(b)

-18\,\text{cm}

(c)

18\,\text{cm}

(d)

15\,\text{cm}