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Solved: Calculate for free electrons with average kinetic
Chapter 42, Problem 22E(choose chapter or problem)
Calculate \(v_{\mathrm{rms}}\) for free electrons with average kinetic energy \(\frac{3}{2} k T\) at a temperature of 300 K. How does your result compare to the speed of an electron with a kinetic energy equal to the Fermi energy of copper, calculated in Example 42.7? Why is there such a difference between these speeds?
Text Transcription:
v_rms
3/2 kT
Questions & Answers
QUESTION:
Calculate \(v_{\mathrm{rms}}\) for free electrons with average kinetic energy \(\frac{3}{2} k T\) at a temperature of 300 K. How does your result compare to the speed of an electron with a kinetic energy equal to the Fermi energy of copper, calculated in Example 42.7? Why is there such a difference between these speeds?
Text Transcription:
v_rms
3/2 kT
ANSWER:Introduction
We have to first calculate the speed of the electrons in given temperature. Then we have to compare the speed with the speed of the electron at the fermi energy level.
Step 1
The average kinetic energy of the electrons at temperature is given by
Here we have
and
Hence the average kinetic energy of the electron is
Now the kinetic energy is also given by
Hence the rms speed of the free electron at the 300 K is m/s.