Calculate the Focal Length of a Concave Mirror

To determine the focal length of a concave mirror when a peanut is placed 11.1 cm away from its center and its image is located 43.9 cm behind the mirror, we can use the lens/mirror equation.

The lens/mirror equation is given by: 1/f = 1/do + 1/di, where f is the focal length, do is the object distance, and di is the image distance.

Substitute the given values into the equation:

1/f = 1/11.1 + 1/-43.9

Solve for f:

1/f = 1/11.1 + 1/-43.9

f = -15.96 cm

Therefore, the focal length of the concave mirror is approximately -15.96 cm. A negative focal length indicates that the mirror is a concave mirror.