Question

When an object is placed at a distance of 50cm
from a concave mirror , the magnification produced
is 0.5 Where should an object be placed to get a
magnification of 1/5?​

Answer 1

Answer:

125 cm from the concave mirror.

Explanation:

Object distance (u) = -50

Magnification = 0.5 = 1/2

As the image has magnification < 1 the image is real.

⇒ M = -1/2

⇒ -v/u = -1/2

⇒ v/u = 1/2

⇒ u = 2v

⇒ -50 = 2v

⇒ v = -25 -----> (1)

Let the value of changed object distance be U

Changed magnification (m) = -1/5 = -v/U

⇒ -(-25)/U = -1/5

⇒ 25/U = -1/5

⇒ U = -125 cm.

∴ The object should be kept at a distance of 125 cm from the concave mirror.