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From YouTube: EOSC 350 DC Lecture 1
Description
First lecture on DC Resistivity by Doug Oldenburg.
A
A
Okay,
everybody's
kind
of
spinning,
so
we're
rap.
We
actually
don't
really
have
very
much
time.
So
there's
only
like
two
weeks
and
lunch
sometime
to
this
kind
of
review
a
little
bit.
So
we're
not
going
to
do
any
more
new
physical
properties
because
actually
electrum
el
electric
conductivity
of
using
city
is
so
important
that
it
will
crop
up
in
here.
A
Lives
and
so
I
want
to
take
the
next
section
and
we're
going
to
do
electrical
conductivity,
but
with
a
different
kind
of
technique
and
then
there's
also
going
to
be
an
extra
little
wrinkle
turns
out
with
the
electrical
conductivity
has
scott
a
little
bit
of
a
3-2
this
its
frequency
dependent.
That
depends
what
pretty
see
you're
trying
to
measure
that,
and
that
gives
rise
to
a
survey
called
induced
polarization
and
probably
for
anybody.
Who's
gone
the
mineral
exploration
in
British
Columbia
or
anybody.
B
A
You've
got
time,
varying
magnetic
field
generating
electric
fields
inside
the
earth
which
give
rise
to
currents
which
give
rise
other
magnetic
fields
that
you
can
measure
and
there's
a
real
part
and
there's
an
imaginary
part,
and
it's
like
whoa,
it's
a
lot
stuff,
so
the
hard
part's
begun
and
now
what
we're
going
to
do
is
to
go
back
and
look
at
that
electrical
conductivity.
But
we're
going
to
do
it
through
a
different
technique.
A
So
what
you
had
done
before
was
we
had
a
transmitter
here,
just
a
loop,
correct
right
and
that
gave
rise
to
this
time
varying
magnetic
field
which
then
generated
currents.
You
know
that
would
flow
inside
the
the
earth.
Those
currents
give
rise
to
magnetic
fields
and
if
we
had
you
know
something
else
that
could
measure
those
fields,
we
could
actually
calculate
what
the
electrical
conductivity
was
and
remember.
A
We
had
this
formula
that,
if
the
distance
between
these
two,
so
if
asked,
was
much
less
than
Delta,
where
Delta
was
that
skin
down
that
we
could
take
the
ratio
of
this
secondary,
feel
to
the
primary
field
and
I
forgot
exactly
what
we
did
here
as
far
as
I.
Don't
know,
there's
some
constants
in
here,
but
we
could
relate
this
measurement
value
to
things
that
we
knew
and
actually
get
out
a
conductivity,
so
that
was
kind
of
cool
right.
A
So
we
have
this
instrument
we
go
along
and
we're
measuring
a
number
here
which
we
can
convert
to
conductivity,
so
you're
getting
information
by
not
actually
exactly
so.
What
we
want
to
do
now
is
the
same
thing,
except
it's
going
to
be
just
a
little
bit
different
instead
of
having
this
loop
source
out
here
and
which
sometimes
we
refer
to
that
as
an
inductive
source,
because
it's
inducing
currents
in
here
we
could
do
the
following.
A
We
could
take
a
probe
and
we
can
hook
it
up
to
a
battery
or
a
generator,
and
we
could
have
another
current
or
another
electrode
here.
So
we
take
a
battery.
Put
one
end
up
to
the
earth
hook.
Another
end
up
to
the
ER.
So
now
we've
got,
we've
got
a
circuit,
so
it's
the
same
kind
of
thing
that
you'd
have.
If
you
have
just
a
usual
circuit,
you
know:
you'd
have
some
kind
of
a
resistor
got
battery
here,
so
we've
got
some
kind
of
the
current
that's
flowing
through
here.
A
We'd
have
a
complete
circuit.
We
could
do
the
same
with
your
it's
just
that
we're
kind
of
using
this
whole
earth
background
and
say
yeah
a
big
as
a
big
resistor,
but
certainly
you
could
try
this
try
this
mom,
you
could
take
big
battery.
You
could
take
two
frogs
and
you
could
take
a
look,
a
bolt
meter.
We
could
take
current
meter,
put
it
in
there
and
you
find
it
oh
you're
actually
going
to
get
a
return.
Her
there's
going
to
be
current
and
circulating.
A
So
that's
what
we're
going
to
do
this
time
we're
going
to
do
the
following:
we're
going
to
take
this
kind
of
system
hook
it
up
to
two
electrodes
and
we're
going
to
call
the
positive
electrode,
the
a
electrode
and
the
negative
electrode,
the
B
electrode.
So
that's
part
of
a
part
of
our
circuit
and
then,
when
that
happens,
I
mean
just
kind
of
intuitively.
The
currents
got
to
get
from
from
here
to
here.
So
you
know
some
of
the
light
travel
along
here
come
my
travel
along
there.
A
So
I
want
to
spend
just
today
kind
of
playing
around
with
an
app
and
then
you
will.
You
can
be
able
to
download
this
over
the
weekend.
So
if
you
get
tired
of
doing
a
whole
bunch
of
other
things,
you
can
kind
of
pull
this
guy
up
and
sit
down
and
you
know
just
play
and
look
at
some
images
and
sort
of
get
a
feeling
for
it
and
the
gpg
has
been
just
read
out.
So
it's
a
much
tinier
information
piece
now.
So
you
know
with
the
app
with
the
gpg:
just
have
a
mental.
B
A
From
everything
else
and
play
around
with
some
physics,
so
so
what
do
we
got
here?
There
is
an
outline
of
a
sphere
we're
going
to
ignore
that
for
now
and
we're
looking
at
and
hurt.
So
this
is
the
X
direction.
That's
the
Z
direction
and
plotted
in
here
as
the
resistivity
in
own
leaders,
and
the
screen
indicates
that
it's
500
ohm
leaders
on
the
bars
here
we've
got
an
A
and
a
B.
So
that's
our
current
current
electrodes,
so
the
a
electrode
is
here
at
minus
30.
A
The
electrode
is
here
at
at
30
and
there's
a
couple
of
things
that
we
need.
We,
we
need
to
know
the
ROE,
the
resistivity
of
this
cylinder
potentially
and
the
role
of
the
of
the
half-space.
These
things
are
both
just
got
500
so
effectively
were
at
a
half
space.
So
that's
the
initial
initial
geometry.
And
now
what
we're
going
to
do
is
put
a
current
in
here
and
then
we
could
look
to
see.
Okay,
where
are
the?
A
B
A
If
we
take
a
positive
electrode
here,
so
here's
our
dinner
and
I'm
here
is
the
negative.
You
can
see
it's
comfortable
what
I
just
sketched
out
there.
So
this
is
the
direction
of
the
currents
inside
the
earth.
You
got
to
go
for
the
plus/minus
and
somehow
they're
just
going
to
kind
of
get
distributed.
A
A
B
A
B
A
You're
talking
about
resistivity
means
it's
hard
for
current
flow
through
current
still
wants
to
go
from
here
to
here,
whereas
before
it
was
kind
of
going
through
like
this,
it's
now
yeah
and
you
might
expect
it
to
kind
of
go
around.
You
probably
have
some,
that's
that
that's
going
through,
but
you
know
that's
sort
of
the
kind
of
thing
that
you
would
do.
A
B
A
A
A
A
A
A
And
that,
if
ya
over
so
there's,
there's
a
lectric
potential,
that
I
is
related
to
the
distance
that
you
are
from
from
kurt's
orbs,
and
there
is
a
singularity
such
that
the
potential
reaches
a
high
value
right
at
application
of
that
current
and
then
drops
off
as
as
1
upon
launch,
so
that
the
voltage
kind
of
falls
off
as
one
of
hamar.
And
if
you
had
a
negative
current
that's
sitting
out
here,
then
it
would
have
a
voltage
that
looks
so.
A
A
A
So
I'm
going
to
say
that's
a
transient,
so
I'm
going
to
keep
track
of
all
my
electrodes
I've
got
current
electrodes
and
I'm
going
to
add
potential
electrodes
imminent,
so
the
distance
between
the
current
electrode
a
and
the
potential
xcode
areas
of
it
by
this.
So
that
would
be
the
voltage
that
I
would
get
ya
get
from
here.
If
I
was
going
to
look
at
a
potential.
A
A
So
now
I've
got
at
any
particular
point
here,
whatever
my
potential
is
due
to
these
two
current
electrons.
Unfortunately,
if
I
measure-
and
you
know
what
happens
to
that,
if
you
take
your
little
boat
either
and
you
just
put
one
end
to
a
battery,
you
know
you
can't
get
any
reading,
you
need
to
make
potential
difference.
So
what
we'll
do
here
is
have
the
other
end
of
the
potential
electrode
would
be
like
this
and
now
here
we're
going
to
measure
the
voltage.
A
So
if
I
take
this
measurement
here,
I
take
this
potential
difference
and
compute
it.
What
that
total
of
difference
voltage
is
I'm
just
going
to
get
number
that
looks
like
this,
so
I'm
going
to
get.
Some
number
is
equal
to
roll
the
resistivity
the
current
times.
This
factor
here,
which
is
just
it's
just
a
geometric
factor.
It's
like
1
over
the
distance
between
the
a
and
M
electrode
and
electrodes.
So
we
just
have
these
numbers
here.
So
I
could
reformulate
this
into
a
different
formulation.
A
A
A
A
So
here
we've
got
a
uniform,
half-space,
500
0
meters.
Here's
my
my
potential
I'm
going
to
measure
the
disk
difference
between
these
two
numbers.
That's
my
potential
difference
and
I'm
going
to
convert
that
using
that
formula
to
an
apparent
resistivity
and
I'm
going
to
get
500
ohm
leaders,
which
is
what.
A
That
should
be
enough
for
you
to
kind
of
go,
and
you
can
take
a
look
at
this
app
just
playing
with
a
few
things
you
what's
going
to
will
be
interesting
is,
if
you
make
these
layers
of
get
different,
conductivity
or
resistivity,
or
you
do
the
same
thing
with
the
with
the
cylinder
and
you'll.
Take
a
look
at
what
apparent
resistivities
that
you
get
out
and
you'll
be
able
to
start
to
kind
of
get
this
connection
between,
know
the
currents
and
the
resultant
appearances.