To determine the focal length of a concave mirror by far away image.

2. To determine the focal length of a concave mirror by obtaining an image of a far distance object

AIM :- To determine the focal length of a concave mirror by obtaining an image of a far distance object.

APPARATUS  :- A concave  mirror of diameter approximately 10 cm., stand, screen, foot-rule, etc.

PRINCIPLE   :- Rays coming from a far distance object are almost parallel. Such rays, parallel to the principal axis, after being reflected by a concave mirror, are focused at the principal focus of the mirror. Distance between the principal focus and the pole of the mirror is known as the focal length.

NOTE  :  Here screen should be taken small, so that rays coming from the object are    not blocked by the screen itself. Diameter of the screen here can be   approximately 3 – 4 cm.

Focal Length of Concave mirror

Parallal rays of a Image 

Focal length of image on concave mirror

OBSERVATION

Distance between the pole of the mirror and the image on the screen = focal-length =                            CM.

CONCLUSION

PRACTICAL USES

Concave mirrors are used in head lights of vehicles, solar furnace, solar cooker, shaving mrror, etc. For all such applcatons it is necessary to know the focal length of the mirror to used. It can be estimated using the given method.

Video

To determine the focal length of a concave mirror by obtaining an image of a far distance object.

Focal length of concave mirror of a far away image.wmv