Answer to Question #2740 in Optics for erin
A shiny metallic Christmas ball ornament 5.10 cm in diameter is used as a mirror. What is the mirror's focal length? please answer in cm. thank you!
d = 5.1 cm r=d/2=2.55 cm
Shiny metallic ball is a curved mirror.
For the curved mirror F= -r/2 where r is radius of curvature;
Answer: -1.275 cm.