
39-21Magnetic Field Measurement
in resistivity (about 5% maximum). Figure 39.16 illustrates how the resistivity changes in permalloy
(a ni
ckel–iron
al
loy)
fo
r
a e
ld
ap
plied
pa
rallel
to th
e
cu
rrent
o
w
. As ma
gnetic
e
ld
is in
creased,
th
e
ch
ange
in re
sistivity
in
creases
an
d
as
ymptotically
ap
proaches
it
s
ma
ximum
va
lue
wh
en
th
e
ma
terial
ap
proaches
sa
turation
. Bo
zorth
[6
]
po
ints
ou
t
th
at
th
e
sh
ape
of th
e
cu
rve
an
d
th
e
ma
gnitude
of th
e
ch
ange
de
pend
on th
e
co
mposition
of th
e
al
loy
. Pe
rmalloy
wi
th
80
%
Ni an
d
20
%
Fe pr
ovides
a hi
gh
ma
g-
netoresistance
e
ect
w
ith
n
ear-zero
m
agnetostriction
a
nd
i
s
a f
avorite
m
aterial
f
or
m
agnetoresistors
.
e change in resi ...