Question

The wave number of a beam of light in air is $2.5\times {10}^6$ per meter. Find its wavelength in glass if $\mu =1.5$ glass.

• A. $6670$ A.U.
• B. $2670$ A.U.
• C. $8670$ A.U.
• D. $9670$ A.U.

Answer 1

The correct option is B $2670$ A.U.

Given refractive index of glass $\mu$=1.5 and wavelength of light in air$=\frac{1}{2.5\times {10}^6}$=0.4 $\times {10}^{-6}$

From Snell's law we get $\mu =\frac{v_a}{v_m}=\frac{{\lambda }_a}{{\lambda }_m}{\lambda }_m=\frac{0.4\times {10}^{-6}}{1.5}=2666.67\times {10}^{-10}$

=2666.67 $\mathring{A}$