Question

A plane glass mirror of thickness $3cm$ of material of $\mu =3/2$ is silvered on the back surface. When a point object is placed $9cm$ from the front surface of the mirror, then the position of the brightest image from the front surface is

• A. $9cm$
• B. $11cm$
• C. $12cm$
• D. $13cm$

Answer 1

Answer: (D)

A thick glass mirror produces a number of images.
There is an apparent shift of actual silvered surface toward the unsilvered face.
Effective distance of the reflecting surface from unsilvered face
$=\frac{d}{\mu }=\frac{3}{3/2}cm=2cm$
Distance of the point object from effective reflecting surface
$=9cm+2cm=11cm$
Distance of image from the point object
$=11cm+11cm=22cm$
Distance of image from unsilvered face
$=(22-9)cm=13cm$