Question

In a double slit experiment using light of wavelength $600\, nm$, the angular width of a fringe on a distant screen is $0.1^{\circ}$. The spacing between the two slits is

• A. $3.44 \times 10^{-4}\,m$
• B. $1.54 \times 10^{-4}\,m$
• C. $1.54 \times 10^{-3}\,m$
• D. $1.44 \times 10^{-3}\,m$

Answer 1

Answer: (A)

Angular width of fringe,
$\theta = 0.1^{\circ} = 0.1 \times\frac{\pi}{180} rad $
$ = \frac{3.14}{1800}rad $
$ \therefore d = \frac{\lambda}{\theta} $
$ = \frac{600\times 10^{-9}}{3.14/ 1800}$
$ = 3.44 \times 10^{-4} m $