If a metal wire carries a current of 79
.
0 mA,
how long does it take for 7.90
×
10
20
electrons
to pass a given cross-sectional area anywhere
along the wire? The fundamental charge is
1
.
602
×
10
−
19
C.
Answer in units of s
1 amp=1coulomb/sec=1coulomb/e electrons per second
1amp=1/1.603E-19 electrons/sec
= 6.24E18 electrons per second.
so then 79ma=.079amp=.079*6.24E18 electrons/sec
time=electcrons/rate=7.90E20/.079*6.24E18
time=1603seconds
check all that
To find the time it takes for the given number of electrons to pass a cross-sectional area in the wire, we need to use the formula:
t = (n * q) / I
Where:
t = time (in seconds)
n = number of electrons
q = fundamental charge (1.602 × 10^-19 C)
I = current (in amperes)
Given:
Number of electrons (n) = 7.90 × 10^20 electrons
Fundamental charge (q) = 1.602 × 10^-19 C
Current (I) = 79.0 mA = 79.0 × 10^-3 A
Now, we can substitute the values into the formula and solve for time (t):
t = (7.90 × 10^20 * 1.602 × 10^-19) / (79.0 × 10^-3)
Simplifying the equation, we get:
t = 12645.6 / 0.079
t = 160203.8 seconds
Therefore, it takes approximately 160203.8 seconds for 7.90 × 10^20 electrons to pass a given cross-sectional area anywhere along the wire.