An object is placed in from of a convex mirror of focal length 9 cm. at a distance of 18 cut. Its image is formed at a distance of:

Correct option is C

The correct answer is (C) 6cm.

• Image formation in convex mirror when the Object is Placed Between Infinity and Pole
• We take into consideration two distinct rays emanating from the object in this instance of the formation of an image by a convex mirror.
• One runs parallel to the principal axis, and the other points in the direction of the mirror's center of curvature.
• After being reflected, the image between the pole (P) and the focus (F) behind the mirror is created by these rays.
• As a result, a diminished, virtual, and erect image is created.

​Calculations Given

a convex mirror focal length,

f=9cm object distance,

u=-18cm

We know,

mirror formula

$${\frac{1}{v}}+ {\frac{1}{u}}= \frac{1}{f}$$​

$${\frac{1}{v}}+ {\frac{1}{-18}} = \frac{1}{9}$$​

$$\frac{1}{v}= {\frac{1}{9}}+{\frac{1}{18}}$$​

$$\frac{1}{v}= {2}+{\frac{1}{18}}= {\frac{3}{18}}$$​

$${\frac{1}{v}}= {\frac{1}{6}}$$​

v= 6cm