Question

In the double slit experiment, the distance between two slits is $0.6mm$ and these are illuminated with light of wavelength $4800A^o$. The angular width of dark fringes on the screen distant $120cm$ from slits will be

• A. $8\times {10}^{-4}$ Radian
• B. $6\times {10}^{-4}$ Radian
• C. $4\times {10}^{-4}$ Radian
• D. $16\times {10}^{-4}$ Radian

Answer 1

The correct option is D $16\times {10}^{-4}$ Radian

For first $(n=1)$ dark fringe,

Angular width $={\theta }_d=2\frac{(2n-1)\lambda }{d}=\frac{2\times \left(1\right)(4800\times {10}^{-10})}{6\times {10}^{-4}}=16\times {10}^{-4}radian$