Module 5 : MODERN PHYSICS
Lecture 26 : Wave Nature of Particle - the de Broglie Hypothesis
  Thus
 
$\displaystyle p_x^\prime-\frac{h}{\lambda^\prime}\sin\theta =p_x^{\prime\prime}+ \frac{h}{\lambda^{\prime\prime}}\sin\theta$
  so that the momemntum uncertainty of the electron is
 
$\displaystyle \Delta p_x = p_x^\prime-p_x^{\prime\prime}=\frac{2h}{\lambda}\sin\theta=\frac{h}{\Delta x}$
  giving
 
$\displaystyle \Delta x\Delta p_x \approx h$
  It may be noted that one can always determine the momentum along the y-direction with any desired degree of accuracy when there is position uncertainty along the x-direction.
Exercise 8
 

Example 17

 
   
18