Which statement best describes a difference between electromagnetic waves
2 answers:
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1) Drift velocity:
2) electrons per person
Explanation:
1)
For a current flowing through a conductor, the drift velocity of the electrons is given by the equation:
where
I is the current
n is the concentration of free electrons
is the electron charge
A is the cross-sectional area of the wire
The cross-sectional area can be written as
where r is the radius of the wire. So the equation becomes
In this problem, we have:
I = 8.0 A is the current
is the concentration of free electrons
d = 1.5 mm is the diameter, so the radius is
r = 1.5/2 = 0.75 mm =
Therefore, the drift velocity is:
2)
The total length of the cord in this problem is
L = 3.00 m
While the cross-sectional area is
Therefore, the volume of the cord is
(1)
The number of electrons per unit volume is , so the total number of electrons in this cord is
In total, the Earth population consists of 8 billion people, which is
Therefore, the number of electrons that each person would get is: