Answer:
65
Explanation:
The resonant frequencies for a fixed string is given by the formula nv/(2L).
Where n is the multiple
.
v is speed in m/s
.
The difference between any two resonant frequencies is given by v/(2L)= fn+1 – fn
fundamental frequency means n=1
i.e fn+1 – fn = 390 -325
= 65
Answer:
The correct answer is 
Explanation:
The formula for the electron drift speed is given as follows,
where n is the number of of electrons per unit m³, q is the charge on an electron and A is the cross-sectional area of the copper wire and I is the current. We see that we already have A , q and I. The only thing left to calculate is the electron density n that is the number of electrons per unit volume.
Using the information provided in the question we can see that the number of moles of copper atoms in a cm³ of volume of the conductor is 
. Converting this number to m³ using very elementary unit conversion we get 
. If we multiply this number by the Avagardo number which is the number of atoms per mol of any gas , we get the number of atoms per m³ which in this case is equal to the number of electron per m³ because one electron per atom of copper contribute to the current. So we get,
if we convert the area from mm³ to m³ we get 
.So now that we have n, we plug in all the values of A ,I ,q and n into the main equation to obtain,
which is our final answer.
I believe that the answer to the question provided above are the following;
x = 29.8410
y = 16.6794
z = -1.2642
Hope my answer would be a great help for you. If you have more questions feel free to ask here at Brainly.
I think it is B i hope it helps
