The difference in the number of wavelengths, when yellow light propagates through air and vacuum columns of the same thickness, is one. The thickness of the air column is : <br> Refractive index of air $\mu_c = 1.0003$ <br> Wavelength of yellow light in vacuum = $6000 \; \mathring{A}$

Question

( A ) 2 cm
( B ) 2.2 cm
( C ) 1.8 mm
( D ) 2 mm