Question

CCE RF & RR
9
83-E
30. An object is kept on the principal axis of a concave mirror of focal length
12 cm. If the object is at a distance of 18 cm from the mirror, calculate the
image distance. Determine the nature of the image formed by calculating
the magnification produced by the mirror,
OR
for
sto
C
n​

Answer 1

Given:

An object is kept on the principal axis of a concave mirror of focal length 12 cm.  

To find:

If the object is at a distance of 18 cm from the mirror, calculate the image distance. Determine the nature of the image formed by calculating the magnification produced by the mirror

Solution:

From given, we have,

The focal length of the mirror = f = -12 cm

The object distance = -u = 18 cm

Using the mirror formula, we have,

1/f = 1/u + 1/v

-1/12 = -1/18 + 1/v

solving the above, we get,

v = -36 cm

The magnification is given by,

m = -v/u = - (-36)/(-18)

∴ m = -2

Nature and the and the size (enlarged or diminished) of the image formed by a concave mirror if the magnification produced by the mirror is -2:  

Nature of the image is inverted (since negative sign) and diminished (since value lesser than 1).