Question

7 10 points A legend says that Archimedes once saved his native town of Syracuse by burning the enemy's fleet with a mirror. Recall that a concave mirror focuses all light coming in parallel to its primary axis down to the focal point. Find the radius of curvature of mirror that Archimedes could have used to burn ships that were 150 m away using parallel light coming into his mirror from the sun. Give an exact answer in m. Type your answer...

Answer 1

Answer:300 m

Solution :

The focal length of a concave mirror is related to its radius of curvature in the following manner.

Radius of Curvature = 2 $\times$ focal length

We are given

focal length = 150 m

So

Radius of curvature = 2$\times$ 150 = 300 m.