Aim : To find the focal length of a concave mirror.
Apparatus required.: Concave mirror, a sheet of paper and meter scale.
- Hold a concave mirror perpendicular to the direction of sunlight.
- Take a small paper and slowly move it in front of the mirror and find out the point where you get smallest and brightest spot.
- This is the image of the sun.
- The rays coming from sun parallel to the concave mirror are converging at a point.
- This point is called focus or focal point (F) of the concave mirror.
- Measure the distance of this spot from the pole of the mirror.
- This distance is the focal length of the given concave mirror.