
18-6 Electrical Variables
forces that the oscillations of the coil in the magnetic eld exert on the coil active sides. It can be
pr
oved[1]
th
at
th
e
os
cillation
da
mping
is a fu
nction
of th
e
co
il
ci
rcuit
re
sistance,
th
at
is
,
th
e
co
il
re
sis-
tance
r pl
us
th
e
eq
uivalent
re
sistance
of th
e
ex
ternal
ci
rcuit
co
nnected
to th
e
ga
lvanometer
. In pa
rticu-
lar,
t
he
d
amping
e
ect
i
s
n
il
i
f
t
he
c
oil
c
ircuit
i
s
o
pen
a
nd
m
aximum
i
f
t
he
c
oil
i
s
s
hort-circuited
.
In pr
actical
sit
uations,
a re
sistor
is co
nnected
in se
ries
wi
th
th
e
mo
ving
co
il,
wh
ose
re
sistance
is
se
lected
in su
ch
a wa
y
to re
alize
a cr
itical
da
mping
of th
e
co
il
mo
vement
. Wh
en
th
is
sit
uation
is ob
ta ...