Question

A glass slab of thickness 12 mm is placed on a table. The lower surface of the slab has a black spot. At what depth from the upper surface will the spot appear when viewed from above? (Refractive index of glass =1.5)

• A. $2mm$
• B. $4mm$
• C. $6mm$
• D. $8mm$

Answer 1

The correct option is D $8mm$

Here it is given,

Read depth $D=12mm$

Refractive index $\mu =1.5$

Let $d$ be the apparent depth then the formula for apparent depth is given by

$\mu =\frac{D}{d}$

$\Rightarrow d=\frac{D}{\mu }=\frac{12}{1.5}=8mm$

Hence the correct answer is option (A).