Two light waves having the same wavelength in vacuum are in phase… - Vidyadip

MCQ

Two light waves having the same wavelength $\lambda$ in vacuum are in phase initially. Then the first wave travels a path $L _{1}$ through a medium of refractive index $n_{1}$ while the second wave travels a path of length $L_{2}$ through a medium of refractive index $n _{2}$. After this the phase difference between the two waves is:

✓
$\frac{2 \pi}{\lambda}\left( n _{1} L _{1}- n _{2} L _{2}\right)$
B
$\frac{2 \pi}{\lambda}\left(\frac{ L _{2}}{ n _{1}}-\frac{ L _{1}}{ n _{2}}\right)$
C
$\frac{2 \pi}{\lambda}\left(\frac{ L _{1}}{ n _{1}}-\frac{ L _{2}}{ n _{2}}\right)$
D
$\frac{2 \pi}{\lambda}\left( n _{2} L _{1}- n _{1} L _{2}\right)$

✓

Answer

Correct option: A.

$\frac{2 \pi}{\lambda}\left( n _{1} L _{1}- n _{2} L _{2}\right)$

a
$\Delta p = n _{1} L _{1}- n _{2} L _{2}$

$\Delta \phi=\frac{2 \pi}{\lambda} \Delta p$

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