The current
I=80A, and the length of the conductor
L=10m.
Expression for Current:
Current can be written as
I=neAVd, where
n is the number of electrons per unit volume,
e is the charge of an electron,
A is the cross-sectional area, and
Vd is the drift velocity of electrons.
Total Number of Electrons:
Let
N be the total number of free electrons in the length
L of the conductor.
N=nAL.
Total Momentum:
The total momentum of all free electrons is
Ptotal=N(meVd), where
me is the mass of an electron.
Substitute
N :
So,
Ptotal=(nAL)(meVd).
Rewrite with Current Expression:
Since
I=neAVd, we can replace
nAVd with
eI.
Therefore,
Ptotal=eILme.
Simplified Formula:
So,
Ptotal=IeLme.
Plug in the Values:
Ptotal=80×1.6×10−1910×9.1×10−31First, multiply
80×10=800.
Now
800×9.1=7280.
So, numerator is
7280×10−31 and denominator is
1.6×10−19.
Divide 7280 by 1.6 to get 4550 .
Power of ten:
10−1910−31=10−12Final Answer:
Ptotal=4550×10−12N-s=4.55×10−9N-s=455×10−11N-s