Question

In a double slit experiment the angular width of a fringe is obtained as ${0.2}^0$ on a screen placed 1m away. The wavelength of light used is 600nm. The angular width of the fringe if the entire experimental arrangement is immersed in water is ( refractive index of water= 1.33)

• A. ${0.15}^0$
• B. ${0.3}^0$
• C. ${0.6}^0$
• D. ${1.2}^0$
• E. ${1.5}^0$

Answer 1

The correct option is A ${0.15}^0$

Given that,

Distance between fringe and screen is, $D=1m$

Wavelength of light, $\lambda =600nm$

Refractive index, $\mu =1.33$

Angular width, ${\theta }_1={0.2}^0$

The relation between angular width and wavelength is

$\frac{{\theta }_2}{{\theta }_1}=\frac{1}{\mu }$

${\theta }_2=\frac{{\theta }_1}{\mu }$

${\theta }_2=\frac{0.2}{1.33}$

${\theta }_2=0.15$