Question

Suggest a method to find approximate focal length of a concave mirror.​

Answer 1

The ray diagram shows the image of a distant object kept in front of a concave mirror. The rays meet at the focus of the mirror and the image is point

Answer 2

Answer:

Place the ray-box well outside the approximate focal length.

Move the screen until a clear inverted image of the crosswire is obtained.

Measure the distance u from the crosswire to the mirror, using the metre stick.

Measure the distance v from the screen to the mirror.