Plot a graph showing variation of de-Broglie ...

CBSE Class 12 Physics 2016 Delhi Set 1 Paper

Question : 7 of 26

Marks: +1, -0

Plot a graph showing variation of de-Broglie wavelength

\lambda

versus

\;\frac{1}{\sqrt{V}}

, where

V

is accelerating potential for two particles

A

and

B

carrying same charge but of masses

m_1, m_2\ (m_1>m_2)

. Which one of the two represents a particle of smaller mass and why ?

Solution:

Plotting of graph

Identification of line representing lower mass

Reason

\lambda = \frac{h}{\sqrt{2 m e V}}

As the charge of two particles is same, therefore

\frac{\lambda}{\left(\frac{1}{\sqrt{V}}\right)} \alpha \frac{1}{\sqrt{m}}

i.e. slope

\alpha \frac{1}{\sqrt{m}}

Hence, particle with lower mass

(m_2)

will have greater slope.

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