Question

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

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

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
$=\frac{d}{\mu}=\frac{3}{3 / 2} cm =2 \,cm$
Distance of the point object from effective reflecting surface
$=9 \, cm +2 \,cm =11 \,cm $
Distance of image from the point object
$=11 \, cm +11 \,cm =22 \, cm$
Distance of image from unsilvered face
$=(22-9) cm =13 \,cm$