Question

When the same monochromatic ray of light travels through glass slab and through water, the number of waves in glass slab of thickness $6cm$ is same as in water column of height $7cm$. If refractive index of glass is $1.5$ then refractive index of water is :

• A. $1.258$
• B. $1.269$
• C. $1.286$
• D. $1.310$

Answer 1

Answer: (C)

$1.286$

No. of waves is glass slab = No. of waves in water column

${\mu }_g{h}_g={\mu }_w{h}_w$

${\mu }_w=\frac{{\mu }_g{h}_g}{h_w}=\frac{1.5\times 6}{7}=1.286$