Question

In YDSE experiment slits are replaced by electron gun emitting electrons at speed ${10}^{7}m/s$. Slit seperation was $0.5mm$ and screen is at $1m$ from gun. Fringe width obtained at screen due to interference is approximately

• A. $200\times {10}^{-9}m$
• B. $1.45\times {10}^{-7}m$
• C. $3.4\times {10}^{-10}m$
• D. $1.56\times {10}^{-6}m$

Answer 1

The correct option is B $1.45\times {10}^{-7}m$

$\lambda =\frac{h}{p}=\frac{6.6\times {10}^{-34}}{9.1\times {10}^{-31}\times {10}^7}=0.725\times {10}^{-10}m$

$w=\frac{\lambda D}{d}=\frac{0.725\times {10}^{-10}}{0.5\times {10}^{-3}}=1.45\times {10}^{-7}m$