Reflection & Refraction (C10)

A 5 cm tall object is placed at a distance of 30 cm from a convex mirror of focal length 15 cm. Find the position, size and nature of the image formed.

Answer

h1 = +5 cm ; u = −30 cm ; f = +15 cm; v = ?

1/f = 1/v + 1/u

1/v = 1/f - 1/u

= 1/(+15) - 1/(-30)

= 1/15 + 1/30

= 1/10

∴ v = +10 cm

h2/h1 = - v/u

h2 = - (+10)/(-30) × (+5)

h2 = +5/3 = +1.66 cm

Nature - virtual, erect