Question

The difference in the number of waves when yellow light propagates through air and vacuum columns of the same thickness is one. The thickness of the air column is ____ $mm$.
[Refractive index of air $=1.0003$, wavelength of yellow light in vacuum $=6000\mathring{A}$ ]

Answer 1

Answer: 2

Thickness $t=n\lambda$
So, $n{\lambda }_{\text{vac }}=(n+1){\lambda }_{\text{air }}$
$n\lambda =(n+1)\frac{\lambda }{{\mu }_{\text{ air }}}$
$n=\frac{1}{{\mu }_{\text{air }}-1}=\frac{10^4}{3}$
$t=n\lambda$
$=\frac{10^4}{3}\times 6000\mathring{A}$
$=2mm$