Question

In Young's double slit experiment, angular width of fringes is ${0.20}^o$ for sodium light of wavelength $5890\stackrel{o}{A}$. If complete system is dipped in water, then angular width of fringes becomes.

• A. ${0.15}^o$
• B. ${0.22}^o$
• C. ${0.30}^o$
• D. ${0.11}^o$

Answer 1

Answer: (A)

${0.15}^o$

b'Angular fringe width$=\theta =\frac{\lambda }{d}$
$\Rightarrow \theta \propto \lambda$
${\lambda }_w=\frac{{\lambda }_a}{{\mu }_w}$
So, ${\theta }_w=\frac{{\theta }_{air}}{{\mu }_w}=\frac{0.20}{\frac{4}{3}}={0.15}^o$'