## Physics: Principles with Applications (7th Edition)

a. The power of the lens is defined by equation 23–7. $$P=\frac{1}{f}=\frac{1}{0.325m}=3.08D$$ The lens power is positive; this is a converging lens. b. Use equation 23–7. $$P=\frac{1}{f}$$ $$f=\frac{1}{D}=\frac{1}{-6.75D}=-0.148m$$ The focal length is negative; this is a diverging lens.