Question

1. A concave mirror has a 7.0 cm focal length.  A 2.4 cm object is 16.0 cm from the mirror.  Determine the image height.

Answer 1

The mirror equation says

$$\frac{1}{d_i}+\frac{1}{d_o}=\frac{1}{f}$$

$$\frac{1}{d_o}=\frac{1}{f}-\frac{1}{d_i}$$

$$\frac{1}{d_o}=\frac{1}{7.0}-\frac{1}{16}$$

$$d_o=12\:\rm cm$$

$$\frac{h_i}{h_o}=\frac{d_i}{d_o}$$

$$h_i=h_o\frac{d_i}{d_o}=2.4*\frac{12}{16}=1.9\:\rm cm$$