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Current and Resistance
75
17.5
The period of the electron in its orbit is
2
r
T
v
π
=
, and the current represented by the
orbiting electron is
()
(
)
61
9
3
11
2
2.19
10 m s
1.60
10
C
1.05
10
C s
1.05 mA
25
.
2
91
0
m
ev
e
Q
I
tT
r
−
−
−
∆
==
=
∆
××
×
×
=
17.6
The mass of a single gold atom is
-22
-25
23
197 g mol
3.27
10
g
3.27
10
kg
6.02
10
atoms mol
atom
A
M
m
N
=×
×
The number of atoms deposited, and hence the number of ions moving to the negative
electrode, is
3
21
-25
3.25
10
kg
9.93
10
3.27
10
kg
atom
m
n
m
−
×
=
×
×
Thus, the current in the cell is
( )
21
19
9.93
10
1.60
10
C
0.159 A

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