A glass slab of thickness $4 \mathrm{~cm}$ contains the same number of waves as in 'x' cm of water column…
A glass slab of thickness $4 \mathrm{~cm}$ contains the same number of waves as in 'x' cm of water column when both are transversed by the same monochromatic light. If the
refractive indices of glass and water for that light are $\frac{5}{3}$ and $\frac{4}{3}$ respectively, the
value of $\mathrm{x}$ will be
$\frac{9}{20} \mathrm{~cm}$
$\frac{5}{4} \mathrm{~cm}$
$5 \mathrm{~cm}$
$\frac{20}{9} \mathrm{~cm}$
Solution
Correct option is D)
Number of waves in glass slab = number of waves in water
$\mu_{1} \mathrm{~d}_{1}=\mu_{2} \mathrm{~d}_{2}$
$\frac{5}{3} \times 4=\frac{4}{3} \times x$
$\mathrm{x}=5 \mathrm{~cm}$