Question

Where does the mirror needs to be placed in a medium having refractive index $4/3$ (i.e. $x$), if image is to be formed at same place as object $O$?

• A. $2\text{cm}$
• B. $3\text{cm}$
• C. $5\text{cm}$
• D. $6\text{cm}$

Answer 1

The correct option is B $3\text{cm}$


If image is need to be at the object place, then, object need to be placed at the centre of curvature i.e.,

$u=15\text{cm}$

And we know that

Apparent depth $=\mu \times$ actual depth

$\Rightarrow h_i=\mu \times h_o$

$\Rightarrow h_i=\frac{4}{3}\times 9=12\text{cm}$

$\therefore h_i+x=15$

$\Rightarrow x=15-12=3\text{cm}$

Hence, the right option is $\left(b\right)$.