Question

When a glass slab is placed on a cross made on a sheet, the cross appears raised by 1 cm. The thickness of the glass is 3 cm. Then the refractive index of glass is :

• A. $3$
• B. $\frac{3}{2}$
• C. $2$
• D. $\frac{3}{\sqrt{2}}$

Answer 1

Answer: (B)

$\frac{3}{2}$

Separation (x) = 1 cm

Thickness (t) = 3 cm

Refractive index is given by the formula,

$x=t\left(1-\frac{1}{\mu }\right)$

Substituting the values,

$1=3\left(1-\frac{1}{\mu }\right)$

$\frac{1}{3}=1-\frac{1}{\mu }$

$\frac{2}{3}=\frac{1}{\mu }$

$\mu =\frac{3}{2}$

The refractive index of the glass slab is $\frac{3}{2}$.