A) \[{{10}^{-5\,}}\,m/s\]
B) \[{{10}^{2}}\,m/s\]
C) \[{{10}^{8}}\,m/s\]
D) \[{{10}^{5}}\,m/s\]
Correct Answer: D
Solution :
Thermal energy of free electron is \[=\frac{3}{2}kT\] Let \[\upsilon \] be the thermal speed of electron, then \[\frac{1}{2}m{{\upsilon }^{2}}=\frac{3}{2}kT\] \[\upsilon =\sqrt{\frac{3kT}{m}}\] \[\Rightarrow \]\[\upsilon =\sqrt{\left[ \frac{3\times 1.38\times {{10}^{-23}}\times 300}{9.1\times {{10}^{-31}}} \right]}\] \[={{10}^{5}}\,m/s\]
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