Question

In a double slit experiment when light of wavelength $400nm$ was used the angular width of the first minima formed on a screen placed $1m$ away was found to be $0.2°$. What will be the angular width of the first minima, if the entire experimental apparatus is immersed in water? (${\mu }_{water}$ = 4/3)

• A. $0.266°$
• B. $0.15°$
• C. $0.05°$
• D. $0.1°$

Answer 1

The correct option is B $0.15°$

Angular width,$\left(\theta \right)=\frac{\lambda }{d}\frac{{\theta }_w}{{\theta }_{air}}=\frac{{\lambda }_w}{{\lambda }_{air}}=\frac{{\mu }_{air}}{{\mu }_w}\frac{{\theta }_w}{0.2}=\frac{3}{4}\times 1\Rightarrow {\theta }_w=0.15°$