Question

In Young's double-slit experiment, the angular width of a fringe formed on a distant screen is $1^o$. The slit separation is 0.01 mm. The wavelength of the light is

• A. 0.174 nm
• B. $0.174\stackrel{0}{A}$
• C. $0.174\mu m$
• D. $0.174\times {10}^{-4}m$

Answer 1

The correct option is C $0.174\mu m$

Angular fringe width, $\theta =\frac{\lambda }{d}$
$\therefore \lambda =\theta d$
Here, $d=0.01mm={10}^{-5}m,\theta =1^{\circ }=\frac{\pi }{180}radians$
$\lambda =\frac{\pi }{180}\times {10}^{-5}=1.74\times {10}^{-7}m$
$=0.174\times {10}^{-6}m=0.174\mu m$