Calculating number of free electrons in metals

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To calculate the number of free electrons in sodium, the resistivity value of 4.2 x 10^-6 ohm-cm is used alongside the Drude model. The first part of the calculation, determining free electrons per cubic centimeter, can be solved using the resistivity formula. For the second part, to find the number of free electrons per atom, one must calculate the number of atoms per cubic centimeter using sodium's density and atomic mass. Units are essential for accuracy in these calculations. The discussion emphasizes the importance of using proper formulas and values to arrive at the correct results.
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Hello everyone, I need your help on a question. The question is "calculate the number of free electrons per cubic centimeter (and per atom)for sodium from resistance data(relaxation time= 3.1Exp-14s)
 
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Just use the formula for resisitvity. Probably you are using the Drude model.
And you need to look up the value of resistivity.
And better post this in the homework section.
 
nasu said:
Just use the formula for resisitvity. Probably you are using the Drude model.
And you need to look up the value of resistivity.
And better post this in the homework section.
Yea I was using the drude model. I know the value of resistivity of sodium to be 4.2Exp-6
 
Then what is your problem?
Some units won't hurt.
 
nasu said:
Then what is your problem?
Some units won't hurt.
I was able to solve the 1st part but he second part (per atom) kind of eludes me
 
eforma said:
I was able to solve the 1st part but he second part (per atom) kind of eludes me
Oh, you can find the number of atoms per cubic cm from density and atomic mass.
 
Thread 'Correct statement about size of wire to produce larger extension'

Thread 'Correct statement about size of wire to produce larger extension'

The answer is (B) but I don't really understand why. Based on formula of Young Modulus: $$x=\frac{FL}{AE}$$ The second wire made of the same material so it means they have same Young Modulus. Larger extension means larger value of ##x## so to get larger value of ##x## we can increase ##F## and ##L## and decrease ##A## I am not sure whether there is change in ##F## for first and second wire so I will just assume ##F## does not change. It leaves (B) and (C) as possible options so why is (C)...
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