Topic 12: Direct Current Circuits

aimwellrestΗλεκτρονική - Συσκευές

7 Οκτ 2013 (πριν από 4 χρόνια και 1 μήνα)

133 εμφανίσεις

T
opi
c

12:

D
i
r
e
c
t

C
u
r
r
e
nt

C
i
r
c
u
i
t
s



S
our
c
e
:




C
onc
e
pt
ual

P
hy
s
i
c
s

t
e
xt
book,

l
a
b
book

a
nd
C
P
O

t
e
xt
book
a
nd
l
a
b
book


T
ype
s

of

M
a
t
e
r
i
a
l
s
:




T
e
xt
books
,

l
a
b
books
,

w
or
ks
he
e
t
,

l
a
b/
a
c
t
i
vi
t
y,

de
m
ons
t
r
a
t
i
on,

w
e
bs
i
t
e
s
/
vi
de
o
s

a
nd
good
s
t
or
i
e
s


B
ui
l
di
ng
on:




C
i
r
c
u
i
t
s

a
r
e

t
he

pr
a
c
t
i
c
a
l

a
ppl
i
c
a
t
i
on
of

t
he

e
l
e
c
t
r
i
c

f
or
c
e
s
,

e
l
e
c
t
r
i
c
a
l

pot
e
nt
i
a
l
,

a
nd
c
u
r
r
e
nt

a
nd

r
e
s
i
s
t
a
nc
e

t
opi
c
s
.

A
ppl
i
e
d
t
he
or
y
c
he
c
ks

a
nd
c
onf
i
r
m
s

t
he

s
t
ude
nt

s

unde
r
s
t
a
ndi
ng
o
f

p
r
e
vi
ous

t
opi
c
s
.

A
s

m
or
e

e
l
e
c
t
r
i
c
a
l

de
vi
c
e
s

a
r
e

unde
r
s
t
ood,

l
i
ke

c
a
pa
c
i
t
or
s
,

i
nduc
t
or
s
,

di
ode
s
,

t
r
a
ns
i
s
t
or
s
,

I
C

s

f
ul
l
-
w
a
ve

r
e
c
t
i
f
i
e
r
s
,

a
nd
s
o

on,

t
he

i
m
a
gi
na
t
i
on
o
f

t
he

s
t
ude
nt

be
c
om
e
s

t
he

onl
y
l
i
m
i
t
a
t
i
on

t
o
pos
s
i
bl
e

c
i
r
c
ui
t
s
.

S
t
ude
nt
s

c
a
n
ga
i
n
t
a
l
e
nt

f
r
om

s
i
m
pl
y
w
i
r
i
ng
a

l
a
m
p
t
o

de
s
i
gni
ng
c
om
put
e
r

c
hi
ps
,

w
i
t
h

M
U
C
H

f
ur
t
he
r

s
t
udy
!


L
i
nks

t
o
P
hys
i
c
s
:




M
a
ny
phys
i
c
a
l

a
ppa
r
a
t
us

i
nc
or
por
a
t
e

e
l
e
c
t
r
oni
c

c
i
r
c
ui
t
s

i
nt
o
t
he
i
r

w
or
ki
ngs
.

A

f
e
w

i
nc
l
ude

t
he

opt
i
c
a
l

m
i
c
r
os
c
ope

(
f
or

l
i
ght
i
ng
)
,

a

c
a
r

doo
r

pow
e
r

l
oc
k
(
e
l
e
c
t
r
i
c
a
l

pow
e
r

ne
e
de
d
t
o

phys
i
c
a
l
l
y
l
i
f
t

a
nd
l
ow
e
r

t
he

l
oc
k)
,

di
r
e
c
t
i
ng
e
l
e
c
t
r
ons

i
n
ol
d
T
V

s
e
t
s

(
e
l
e
c
t
r
om
a
gne
t
s

va
r
y
t
he

m
a
gne
t
i
c

f
i
e
l
d
t
o
di
r
e
c
t

be
a
m
)
,

a
nd

s
o
on.


L
i
nks

t
o
C
he
m
i
s
t
r
y


a
nd
B
i
ol
ogy:

O
f
t
e
n,

t
he

onl
y
e
l
e
c
t
r
oni
c

unde
r
s
t
a
ndi
ng
ne
e
de
d
i
n

c
he
m
i
s
t
r
y
a
nd
bi
ol
ogy

i
s

t
he

ope
r
a
t
i
on
o
f

e
qui
pm
e
nt
.

T
hi
s

l
i
s
t

c
oul
d

be

a
n
yt
hi
ng
s
u
c
h
a
s

i
n
m
e
di
c
i
ne
.

H
i
gh
-
t
e
c
h
m
e
di
c
a
l

e
qui
pm
e
nt

i
nc
l
ude
s

t
he

M
R
I
,

t
he

C
A
T

s
c
a
n,

t
he

ul
t
r
a
s
ound
a
nd
t
he

nuc
l
e
a
r

s
t
r
e
s
s

t
e
s
t
.




M
a
t
e
r
i
a
l
s
:

(
a
)

H
e
w
i
t
t

1.

S
pa
r
ky
t
he

E
l
e
c
t
r
i
c
i
a
n

2.

O
hm

S
w
e
e
t

O
hm

3.

P
a
r
a
l
l
e
l

a
nd
S
e
r
i
e
s

C
i
r
c
ui
t
s

4.

G
e
t
t
i
ng
W
i
r
e
d

5.

C
r
a
nki
ng
U
p


(
b)

H
s
u

E
l
e
c
t
r
i
c

C
i
r
c
ui
t
s


(
c
)

M
y
L
a
b

R
e
s
i
s
t
a
n
c
e

U
s
i
ng
S
e
r
i
e
s

a
nd
P
a
r
a
l
l
e
l

C
i
r
c
ui
t
s

w
i
t
h:

1.

L
i
ght

B
ul
bs

(
S
e
r
i
e
s

01,

02
a
nd

1
c
om
bi
na
t
i
on

c
i
r
c
ui
t
)

2.

R
e
s
i
s
t
or
s

i
n
S
e
r
i
e
s

a
nd
P
a
r
a
l
l
e
l



(
d)

W
or
ks
he
e
t

C
i
r
c
ui
t
s


(
e
)

D
e
m
ons
t
r
a
t
i
on

3
-
W
a
y
L
i
ght

S
w
i
t
c
h


(
f
)

V
i
de
os

a
nd
W
e
bs
i
t
e
s

w
w
w
.
gl
e
nbr
ook.
K
12.
i
l
.
us
/
gbs
s
c
i
/
phys
/
C
l
a
s
s
/
B
B
o
a
r
d.
ht
m
l

(
T
hi
s

s
i
t
e

c
ove
r
s

m
os
t

phys
i
c
s

t
opi
c
s

a
s

a
bbr
e
vi
a
t
e
d
t
he
or
y
f
ol
l
ow
e
d
by

que
s
t
i
ons

a
bout

t
he

s
ke
t
c
he
s

a
nd
di
s
c
us
s
i
on
t
ha
t

i
nt
r
oduc
e
d
t
he

t
opi
c

a
ns
w
e
r
s

pr
ovi
de
d;

i
nt
e
r
a
c
t
i
ve

ove
r

t
he

w
e
b.
)


(
g)

G
ood
S
t
or
i
e
s
*

T
opi
c

12:

E
l
e
c
t
r
i
c
a
l

C
i
r
c
u
i
t
s



S
e
r
i
e
s

01



T
hi
ngs

you
ne
e
d:


P
ow
e
r

s
uppl
y
(
1
)


L
a
m
p
(
1
)


C
onne
c
t
or
s

(
3)


A
m
m
e
t
e
r

(
0
-
2

a
m
p)


A
s
s
e
m
bl
e

t
he

c
i
r
c
ui
t
s

be
l
ow

a
nd
r
e
c
or
d

your

obs
e
r
va
t
i
ons
.



a
)































I

=

__________

a
m
p























































































































































b)























































































































I

=

__________

a
m
p



























I
s

t
he

c
ur
r
e
nt

i
n
c
i
r
c
ui
t

a
)

(
l
e
s
s

t
ha
n,

e
qua
l

t
o
,

gr
e
a
t
e
r

t
ha
n)

t
he

c
ur
r
e
nt

i
n
c
i
r
c
ui
t

b
)
?



I
s

t
he

br
i
ght
ne
s
s

of

t
he

l
a
m
p

i
n
c
i
r
c
ui
t

a
)

(
l
e
s
s

t
ha
n
,

e
qua
l

t
o
,

g
r
e
a
t
e
r

t
ha
n)

t
he

b
r
i
ght
ne
s
s

of

t
he

l
a
m
p
i
n
c
i
r
c
ui
t

b)
?



C
onc
l
us
i
on:

W
ha
t

doe
s

t
he

c
ur
r
e
nt

a
nd

br
i
ght
ne
s
s

t
e
l
l

you
a
bout

a

s
e
r
i
e
s

c
i
r
c
ui
t
?

T
opi
c

12:

E
l
e
c
t
r
i
c
a
l

C
i
r
c
u
i
t
s



S
e
r
i
e
s

02



T
hi
ngs

you
ne
e
d:


P
ow
e
r

s
uppl
y
(
1
)


L
a
m
ps

(
2)


C
onne
c
t
or
s

(
4)


A
m
m
e
t
e
r

(
0
-
2

a
m
p)


A
s
s
e
m
bl
e

t
he

c
i
r
c
ui
t
s

be
l
ow

a
nd
r
e
c
or
d

your

obs
e
r
va
t
i
ons
.


a
)















I

=

__________

a
m
p










I
s

t
he

br
i
ght
ne
s
s

of

L
1

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
ha
n)

t
he

b
r
i
ght
ne
s
s

of

L
2?


b)











































I

=

__________
a
m
p




I
s

t
he

br
i
ght
ne
s
s

of

L
1

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
ha
n)

t
he

b
r
i
ght
ne
s
s

of

L
2?


I
s

t
he

l
a
m
p
b
r
i
ght
ne
s
s

i
n
b)

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
ha
n)

t
he

br
i
ght
ne
s
s

i
n
a
)
?


c
)












I

=

__________

a
m
p





I
s

t
he

br
i
ght
ne
s
s

of

L
1

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
ha
n)

t
he

b
r
i
ght
ne
s
s

of

L
2?


I
s

t
he

l
a
m
p
b
r
i
ght
ne
s
s

i
n
c
)

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
ha
n)

t
he

br
i
ght
ne
s
s

i
n
b
)
?


H
ow

d
oe
s

t
he

l
a
m
p
br
i
ght
ne
s
s

of

t
he

S
e
r
i
e
s

02
l
a
m
ps

c
om
pa
r
e

t
o
t
he

br
i
ght
ne
s
s

of

t
he

S
e
r
i
e
s

01

a
c
t
i
vi
t
y?


C
onc
l
us
i
on:


T
opi
c

12:

E
l
e
c
t
r
i
c
a
l

C
i
r
c
u
i
t
s



C
om
bi
na
t
i
o
n
C
i
r
c
ui
t



T
hi
ngs

you
ne
e
d:


P
ow
e
r

s
uppl
y
(
1
)


L
a
m
ps

(
3)


C
onne
c
t
or
s

(
8)


A
s
s
e
m
bl
e

t
he

c
i
r
c
ui
t

be
l
ow

a
nd
r
e
c
or
d
your

obs
e
r
v
a
t
i
ons
.























1)

I
s

t
he

br
i
ght
ne
s
s

of

L
1

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
h
a
n)

t
he

b
r
i
ght
ne
s
s

of

L
2?









H
ow

c
oul
d
you
e
xpl
a
i
n

t
hi
s
?



2)

I
s

t
he

br
i
ght
ne
s
s

of

L
3

(
l
e
s
s

t
ha
n,

e
qua
l

t
o,

gr
e
a
t
e
r

t
ha
n)

t
he

b
r
i
ght
ne
s
s

of

L
1?







H
ow

c
oul
d
you
e
xpl
a
i
n

t
hi
s
?



3)

W
ha
t

doe
s

t
he

br
i
ght
ne
s
s

of

t
he

l
a
m
ps

t
e
l
l

you
a
bo
ut

t
he

c
ur
r
e
nt

t
hr
ough

L
1

a
nd
L
2?



4)

W
ha
t

doe
s

t
he

br
i
ght
ne
s
s

of

L
3
t
e
l
l

you
a
bout

t
he

c
ur
r
e
nt

t
h
r
ough
L
3?



5)

A
ny
ot
he
r

obs
e
r
va
t
i
ons
?

T
opi
c

12:

R
e
s
i
s
t
or
s

i
n
S
e
r
i
e
s

a
nd
P
a
r
a
l
l
e
l



P
ur
pos
e
:





T
o
e
xpe
r
i
m
e
nt
a
l
l
y

de
t
e
r
m
i
ne

how

r
e
s
i
s
t
or
s

c
om
bi
n
e

w
he
n
c
onne
c
t
e
d
i
n
s
e
r
i
e
s

a
nd
pa
r
a
l
l
e
l
.


B
a
c
kgr
ound:



E
l
e
c
t
r
i
c

r
e
s
i
s
t
a
nc
e

i
s

oppos
i
t
i
on
t
o
e
l
e
c
t
r
i
c

c
ha
r
ge
s

m
ovi
ng
t
h
r
ough
a

s
ubs
t
a
nc
e
.


M
e
t
a
l

of
f
e
r
s

l
i
t
t
l
e

r
e
s
i
s
t
a
nc
e

a
nd
gl
a
s
s

of
f
e
r
s

a

l
ot

o
f

r
e
s
i
s
t
a
nc
e
.

M
a
t
he
m
a
t
i
c
a
l
l
y,

O
hm

s

l
a
w

r
e
l
a
t
e
s

pot
e
nt
i
a
l

di
f
f
e
r
e
nc
e

m
e
a
s
ur
e
d
i
n

V
ol
t
s

(
V
)

t
o
c
ha
r
ge

m
ove
m
e
nt

c
a
l
l
e
d
c
ur
r
e
nt

(
I
)

m
e
a
s
ur
e
d
i
n
A
m
pe
r
e
s

(
A
)

a
s

t
he

O
hm

(
!
)

t
ha
t

i
s

s
ym
bol
i
z
e
d
w
i
t
h
t
he

l
e
t
t
e
r

(
R
)
.

G
e
or
ge

O
hm
,

a

hi
gh

s
c
hool

phy
s
i
c
s

t
e
a
c
he
r
,

di
s
c
ove
r
e
d
t
he

r
e
l
a
t
i
ons
hi
p
a
nd
t
hus

ha
s

t
hi
s

r
e
l
a
t
i
ons
hi
p

na
m
e
d
a
f
t
e
r

hi
m
.

T
he

m
a
t
h

r
e
l
a
t
i
ons
hi
p
i
s

t
he
r
e
f
or
e
,

R

=

V
/
I
,

w
hi
c
h
i
s

not

us
e
d
i
n
ou
r

i
nve
s
t
i
ga
t
i
on.


M
a
t
e
r
i
a
l
s
:


O
hm
m
e
t
e
r







































B
r
e
a
dboa
r
d










































C
a
r
bon
R
e
s
i
s
t
or

(
M
e
a
s
ur
i
ng
de
vi
c
e


























(
D
e
vi
c
e

t
o

e
a
s
i
l
y
c
onne
c
t















(
I
ne
xpe
ns
i
ve

de
vi
c
e


t
o
do
r
e
s
i
s
t
a
nc
e
)






























r
e
s
i
s
t
or
s

w
i
t
hout

t
w
i
s
t
i
ng












t
o
l
i
m
i
t

c
ha
r
ge

f
l
ow
)














































A








t
he

w
i
r
e

l
e
a
ds
)



























































































































































10

!




















































































































































































































































B
r
ow
n
(
1)


















































































































































































































































B
l
a
c
k
(
0
)




























































































































B
r
ow
n
(
x1)





























































































































C
ol
or

c
ode

f
o
r

10

!



























































































B











































E
a
c
h
c
ol
um
n
o
f

hol
e
s
,

l
i
k
e

A
,

i
s

i
n
t
e
r
c
onne
c
t
e
d









































s
o
a
ny
w
i
r
e

l
e
a
d
i
ns
e
r
t
e
d

w
i
l
l

be

e
l
e
c
t
r
i
c
a
l
l
y










































c
onne
c
t
e
d
t
o

e
a
c
h
ot
he
r
.

C
ol
um
n
B

i
s

a
l
s
o









































i
nt
e
r
c
onne
c
t
e
d,

but

i
t

i
s

N
O
T

c
onne
c
t
e
d
t
o
A









































or

a
ny
ot
he
r

c
ol
um
n
.


I
n
t
hi
s

l
a
b

onl
y
t
h
r
e
e

10
-
!

r
e
s
i
s
t
or
s

w
i
l
l

be

us
e
d.

B
e
nd
t
he

l
e
a
ds

on
e
a
c
h
r
e
s
i
s
t
or

t
o

l
ook

l
i
ke

t
hi
s
:







T
hi
s

s
ha
pe

w
i
l
l

a
l
l
ow

t
he

s
t
ude
nt

t
o

e
a
s
i
l
y
i
ns
e
r
t

t
h
e

l
e
a
ds

i
nt
o
t
he

b
r
e
a
dboa
r
d.



(
A
)


P
ur
pos
e
:


T
o

de
t
e
r
m
i
ne

how

r
e
s
i
s
t
or
s

c
om
bi
ne

w
h
e
n
c
onne
c
t
e
d
i
n
s
e
r
i
e
s
.



P
r
oc
e
dur
e

(
a
)
:


1.


S
e
l
e
c
t

t
he

pr
ope
r

r
a
nge

on

t
he

ohm
m
e
t
e
r
.

2.


P
l
a
c
e

t
he

t
w
o
l
e
a
ds

of

t
he

r
e
s
i
s
t
or

i
n
t
w
o

s
e
pa
r
a
t
e

c
ol
um
ns
.

3.


T
ouc
h
t
he

t
w
o

pr
obe
s

of

t
he

ohm
m
e
t
e
r

t
o

t
he

t
w
o

e
nds

of

t
he

r
e
s
i
s
t
or

a
t

X

a
nd

Y
.

4.


R
e
c
or
d
va
l
ue

i
n
t
a
bl
e
.

5.


R
e
pe
a
t

f
or

r
e
s
i
s
t
or

2
.

6.


R
e
pe
a
t

f
or

r
e
s
i
s
t
or

3
.





























































D
o
r
e
s
i
s
t
or

1
,

t
he
n
2,

t
he
n
3.










































































































































X
X
X























































































































































































(
a
)





















































































































(
b)






















































































































(
c
)






E
a
c
h
R
e
s
i
s
t
or

!

V
a
l
ue

1



2



3



P
r
oc
e
dur
e

(
b
)
:

1.

C
onne
c
t

r
e
s
i
s
t
or
s

1
a
nd
2
i
n

s
e
r
i
e
s

on
t
he

b
r
e
a
dboa
r
d
(
s
e
e

s
ke
t
c
h)
.

2.

M
e
a
s
ur
e

t
he

c
om
bi
ne
d
r
e
s
i
s
t
a
nc
e

of

t
he

t
w
o
r
e
s
i
s
t
or
s

i
n
s
e
r
i
e
s
.


S
E
R
I
E
S

C
O
N
N
E
C
T
I
O
N








R
e
s
i
s
t
or
s

1
a
nd
2

!

C
om
bi
ne
d
V
a
l
ue


1
+

2
























































































P
r
oc
e
dur
e

(
c
)
:









1.

C
onne
c
t

r
e
s
i
s
t
or
s

1,

2
a
nd

3
i
n

s
e
r
i
e
s

on
t
he

b
r
e
a
dboa
r
d
(
s
e
e

s
ke
t
c
h)
.

2.

M
e
a
s
ur
e

t
he

c
om
bi
ne
d
r
e
s
i
s
t
a
nc
e

of

t
he

t
hr
e
e

r
e
s
i
s
t
or
s

i
n
s
e
r
i
e
s
.


S
E
R
I
E
S

C
O
N
N
E
C
T
I
O
N


R
e
s
i
s
t
or
s

1
a
nd
2

!

C
om
bi
ne
d
V
a
l
ue


1
+

2
+

3




S
E
R
I
E
S

C
onc
l
us
i
on:

L
ooki
ng
a
t

t
he

i
ndi
vi
dua
l

r
e
s
i
s
t
a
nc
e

va
l
ue
s

a
nd
t
he

c
om
bi
ne
d
va
l
ue
,

I

c
onc
l
ude

t
ha
t
:






















______________________________
_____________
________________________























______________________________
_____________________________________


(
B
)

R
e
s
i
s
t
or
s

i
n
P
a
r
a
l
l
e
l


P
r
oc
e
dur
e

(
a
)
:

1.

C
onne
c
t

r
e
s
i
s
t
or

1
a
nd
2

i
n
pa
r
a
l
l
e
l

a
s

s
how
n
i
n
s
k
e
t
c
h
(
d)
.

2.

M
e
a
s
ur
e

t
he

r
e
s
i
s
t
a
nc
e

of

bot
h
r
e
s
i
s
t
or
s

w
he
n
hook
e
d
i
n
a

b
r
a
nc
h.

(
C
ons
i
de
r

a

br
a
nc
h
a
s

pr
ovi
di
ng
m
or
e

t
ha
n

one

pa
t
h
f
or

t
he

c
ha
r
ge
s

t
o
f
ol
l
ow
;

i
f

a

r
oa
d
f
o
r
ks
,

you
c
hoos
e

w
hi
c
h
r
oa
d
t
o

t
a
ke
.
)


M
e
a
s
ur
e

f
r
om

X

t
o

Y
.
























































































































































































































































(
d
)























































































































P
a
r
a
l
l
e
l

(
a
)

(
a
)

R
e
s
i
s
t
or
s

1
a
nd
2

!

C
om
bi
ne
d
V
a
l
ue


1
+

2




C
om
pa
r
e

t
he

i
ndi
vi
dua
l

r
e
s
i
s
t
a
nc
e
s

of

1
a
nd
2

t
o
t
h
e

c
om
bi
ne
d
r
e
s
i
s
t
a
nc
e

of

1
a
nd

2
w
he
n
i
n
pa
r
a
l
l
e
l
.

C
a
n
you
g
i
ve

a

phys
i
c
a
l

r
e
a
s
on?



_____________________________________________________________________


___________________
__________________________________________________



P
r
oc
e
dur
e

(
b
)
:


R
e
pe
a
t

t
he

pa
r
a
l
l
e
l

pr
oc
e
dur
e

w
i
t
h
t
h
r
e
e

r
e
s
i
s
t
or
s

(
no
s
ke
t
c
h
(
e
)

d
r
a
w
n
f
o
r

t
hi
s

one
)
.


(
b)

R
e
s
i
s
t
or
s

1,

2
a
nd
3

!

C
om
bi
ne
d
V
a
l
ue


1
+

2
+

3




C
om
pa
r
e

t
he

i
ndi
vi
dua
l

r
e
s
i
s
t
a
nc
e
s

of

1,

2

a
nd
3

t
o

t
he

c
om
bi
ne
d
r
e
s
i
s
t
a
nc
e

of

1,

2
a
nd
3

w
he
n
i
n
pa
r
a
l
l
e
l
.

C
a
n
you
g
i
ve

a

phys
i
c
a
l

r
e
a
s
on?


_____________________________________________________________________


_____________________________________________________________________



P
A
R
A
L
L
E
L

C
on
c
l
us
i
on:

H
ow

do
r
e
s
i
s
t
or
s

i
n
pa
r
a
l
l
e
l

c
om
bi
ne
?



_____________________________________________________________________


_____________________________________________________________________


T
opi
c

12:

R
e
s
i
s
t
or
s

i
n
P
a
r
a
l
l
e
l

A
ns
w
e
r

S
he
e
t



(
b)


C
onc
l
us
i
on
t
o
R
e
s
i
s
t
or
s

i
n
P
a
r
a
l
l
e
l

L
a
b


S
a
m
pl
e

D
a
t
a
:


(
A
)

S
E
R
I
E
S


(
a
)














E
a
c
h
R
e
s
i
s
t
or

!

V
a
l
ue

1


10.
0

2


10.
0

3


10.
0














(
b
)
















R
e
s
i
s
t
or
s

1
a
nd
2

!

C
om
bi
ne
d
V
a
l
ue


1
+

2


20.
0


(
c
)

















R
e
s
i
s
t
or
s

1,

2
a
nd
3

!

C
om
bi
ne
d
V
a
l
ue


1
+

2
+

3


30.
0



S
E
R
I
E
S

C
O
N
C
L
U
S
I
O
N
:

A
s

r
e
s
i
s
t
or
s

a
r
e

c
onne
c
t
e
d
i
n
a

r
ow
,

one

a
f
t
e
r

a
not
he
r
,

t
he

s
e
r
i
e
s

c
om
bi
na
t
i
on
i
s

t
he

s
um

of

e
a
c
h
r
e
s
i
s
t
or
.

A
dd
r
e
s
i
s
t
or
s

i
n
s
e
r
i
e
s

t
o
obt
a
i
n

t
he

t
ot
a
l

r
e
s
i
s
t
a
nc
e
.



(
B
)

P
A
R
A
L
L
E
L


(
a
)


R
e
s
i
s
t
or
s

1
a
nd
2

!

C
om
bi
ne
d
V
a
l
ue


1
+

2


5.
0




C
om
pa
r
e
:

T
he

r
e
s
i
s
t
a
nc
e

of

t
he

pa
r
a
l
l
e
l

br
a
nc
h

w
e
nt

dow
n.

S
i
nc
e

c
ha
r
ge
s

ha
ve

a

c
hoi
c
e



of

t
w
o
pa
t
hs
,

t
he

r
e
s
i
s
t
a
nc
e

de
c
r
e
a
s
e
s
.



(
b)




















R
e
s
i
s
t
or
s

1,

2
a
nd

3

!

C
om
bi
ne
d
V
a
l
ue


1
+

2
+

3


3.
3


C
om
pa
r
e
:


T
he

r
e
s
i
s
t
a
nc
e

w
i
t
h
a

t
hi
r
d
pa
t
h

w
e
nt

do
w
n
e
ve
n
m
or
e
.

N
ow

t
ha
t

c
ha
r
ge
s

ha
ve

t
hr
e
e

opt
i
ons
,

oppos
i
t
i
on

i
s

l
e
s
s

t
o
m
ove

t
hr
ough
t
h
e

br
a
nc
h.



P
A
R
A
L
L
E
L

C
O
N
C
L
U
S
I
O
N
:

W
he
n
m
or
e

pa
t
hs

a
r
e

o
f
f
e
r
e
d

a
c
r
os
s

a

pa
r
a
l
l
e
l

br
a
n
c
h,

t
he

r
e
s
i
s
t
a
nc
e

be
c
om
e
s

s
m
a
l
l
e
r

a
nd
s
m
a
l
l
e
r
.

T
he

a
c
t
ua
l

r
e
l
a
t
i
on

of





1/
R







=


1/
R







+


1/
R






+




.

.

.














T
ot
a
l
















O
ne


















T
w
o


m
i
ght

be

r
e
c
ogni
z
e
d
by
s
om
e

m
a
t
he
m
a
t
i
c
a
l
l
y
-
m
i
n
de
d
s
t
ude
nt
s

s
i
nc
e

w
e

ha
ve

us
e
d
a
n
e
a
s
y
s
e
t

of

r
e
s
i
s
t
a
nc
e
s
,

10.
0
!
,

t
hr
e
e

t
i
m
e
s
.



























T
opi
c

12:

A
c
t
i
v
i
t
y



3
-
W
a
y
L
i
g
ht

S
w
i
t
c
h”



P
ur
pos
e
:

T
o
gi
ve

s
t
ude
nt
s

a


pr
a
c
t
i
c
a
l

c
ha
l
l
e
nge


i
n
w
i
r
i
ng

t
ha
t

ha
s

m
e
a
ni
ng


M
a
t
e
r
i
a
l
s
:




(
T
w
o)

3
-
w
a
y
l
i
ght

s
w
i
t
c
he
s


O
hm
m
e
t
e
r


S
A
F
E

D
C

o
r

A
C

l
ow
-
vol
t
a
ge

pow
e
r

s
uppl
y
(
l
i
ke

6
V

or

12V

-

D
O

N
O
T

U
S
E

120
V
A
C


T
O
O

D
A
N
G
E
R
O
U
S
.
)


3,

4
,

5

or

6

c
onne
c
t
i
ng
w
i
r
e
s


S
c
r
e
w
dr
i
ve
r


T
a
s
k:

T
hi
s

i
s

t
he

t
ype

of

c
ha
l
l
e
nge

t
ha
t

s
houl
d
us
e

t
he


i
nqui
r
y”

a
ppr
oa
c
h.

T
he

s
t
ude
nt

a
s
s
i
gnm
e
nt

c
oul
d
be
:


(
a
)


E
xpe
r
i
m
e
nt

w
i
t
h

t
he

p
r
ovi
de
d
m
a
t
e
r
i
a
l
s

t
o
c
onne
c
t

a

c
i
r
c
ui
t

t
ha
t

S
I
M
U
L
A
T
E
S

a

s
w
i
t
c
h
a
t

t
h
e

bot
t
om

of

a

s
t
a
i
r
w
a
y
a
nd
one

a
t

t
he

t
o
p
of

a

s
t
a
i
r
w
a
y
s
o
t
he

l
i
g
ht

c
a
n
be

t
ur
ne
d
on

or

of
f

f
r
o
m

e
i
t
he
r

t
he

t
op

or

bot
t
o
m

of

t
he

s
t
a
i
r
w
a
y
a
nd

(
b)


S
ke
t
c
h
a
l
l

pos
s
i
bl
e

c
i
r
c
ui
t
s
.

(
c
)

S
how

your

c
om
p
l
e
t
e
d
c
i
r
c
ui
t

t
o
t
he

t
e
a
c
he
r
.


R
e
s
ul
t
s
:



S
i
m
pl
i
f
i
e
d
S
w
i
t
c
h:



































































O
n



















































































O
f
f


























































C
om
m
on









































































C
om
m
on


























































O
f
f























































































































































































































O
n





























































O
N

r
i
ght























































O
N

l
e
f
t























































































































































F
our

P
os
s
i
bl
e

C
onne
c
t
i
ons
:















































O
N





































O
F
F










O
F
F










O
N