Question

In a Young’s double slit experiment an electron beam is used to obtain interference pattern. If the speed of electron deceases then:

• A. Distance between two consecutive fringes remains the same
• B. Distance between two consecutive fringes decreases
• C. Distance between two consecutive fringes increases
• D. None of these

Answer 1

Answer: (C)

Distance between two consecutive fringes increases

Answer 2

: Fringe width , $\beta = \frac{\lambda D}{d}$

Also, $\lambda = \frac{h}{mv}$

Here h is Planck’s constant. This wavelength is inversely proportional to the velocity. Hence , the fringe width increases with decreases in electron speed