A spherical Christmas tree ornament is

5.34 cm in diameter.
What is the magnification of the image of
an object placed 10.3 cm away from the ornament

1 answer

The focal length is f = -R/2 = -1.33 cm
The object distance is do = 10.3 cm

1/10.3 + 1/di = 1/f = -1/1.33

Solve for image distance, di. It will be negative (behind the ornament)

Magnification = |di/do|