JEE Mains · Physics · STD 12 - 10. Wave optics
A parallel beam of electrons travelling in \(x-\) direction falls on a slit of width \(d\) (see figure) . If after passing the slit, an electron acquires momentum \(P_y\) in the \(y-\) direction then for a majority of electrons passing through the slit ( \(h\) is Planck's constant)
- A \(\left| {{P_y}} \right|d > h\)
- B \(\left| {{P_y}} \right|d < h\)
- C \(\left| {{P_y}} \right|d \simeq h\)
- D \(\left| {{P_y}} \right|d > > h\)
Answer & Solution
Correct Answer
(A) \(\left| {{P_y}} \right|d > h\)
Step-by-step Solution
Detailed explanation
From Bragg's equation \(d \sin \theta=\lambda\) \(\sin \theta=\frac{\lambda}{d}<1\) \(\therefore \lambda < d\) \(\frac{h}{{\left| {{p_y}} \right|}} < d\) \(\left[ {\because \lambda = \frac{h}{{\left| {{p_y}} \right|}}} \right]\) \(\therefore \quad h<\left|p_{y}\right| d\)
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