Question

An object is placed at a certain distance on the principal axis of a concave mirror. The image is formed at a distance of 30cm from the mirror. Find the object distance if radius of curvature R=15cm.​

Answer 1

Object distance, u = -6 cm

Explanation:

Given that,

The radius of curvature, R = 15 cm

The radius of the mirror, f = -7.5 cm

We need to find the object's distance from the mirror. The mirror's formula is used to find the object distance such that,

`(1)/(f)=(1)/(u)+(1)/(v)\\\\(1)/(u)=(1)/(f)-(1)/(v)\\\\(1)/(u)=(1)/((-7.5))-(1)/(30)\\\\u=-6\ cm`

So, the object distance is 6 cm.