Define principal focus of a spherical mirror

(a) Define principal focus of a spherical mirror.
(b) For what position of the object does a concave mirror form a real, inverted and diminished image of the object? Draw the ray diagram.
© An object 4 cm high is placed at a distance
of 6 cm in front of a concave mirror of focal length 12 cm. Find the position of the image formed.

(a) A number of rays parallel to the principal axis after reflection from a concave mirror meet at a point on the principal axis or appear to come from a point after reflection from a convex mirror on the principal axis. This is called principal focus.
(b) When the object is placed beyond C.

© f = - 12 cm, u = - 6 cm, v = ?

Using the expression

1/f = 1/v - 1/u , we have

1/-12 = 1/v - 1/-6

v = 12 cm

1 Like

Can you please write it in a more easy way.

this is the easiest way one can explain.