Owner manual
-
120
-
The circuit in this experiment allows you to hea
r
alternatin
g
current. You probably know that th
e
e
l
ectr
i
c power runn
i
ng t
h
roug
h
your
h
ome
i
s a
n
alternating current. All your appliances that receiv
e
power from electric outlets operate on AC- includin
g
lamps. Lamps actually flicker at the rate of 60 time
s
per second, but it looks constant because our eye
s
see a
f
ter images. In this experiment you will hea
r
sound converted
f
rom light
.
Ready to start? A
f
ter constructing this circuit, turn on
the power to your kit by settin
g
the switch to A. Plac
e
the CdS cell near an electric lamp. Do you hear
a
hissing sound coming
f
rom the earphone? This is th
e
sound of the alternatin
g
current. Now place the Cd
S
cell under a fluorescent lam
p
, and listen for a simila
r
sound
.
This circuit
g
reatly intensifies the si
g
nals of li
g
ht on
the
C
d
S
cell through the operational amplifier. Adjust
the quantity of light on the CdS cell with your hand
.
You can probably hear the volume of the hissin
g
sound reduce and the quality o
f
the sound improve.
S
ee what occurs when you expose the
C
d
S
t
o
sun
li
g
h
t
.
No
t
es
:
EXPERIMENT #1
00
: LI
S
TEN T
O
ALTERNATIN
G
CU
RREN
T
Schemati
c
Wiring
S
equence
:
15
-
88
-11
3
8
7-
63
-1
31
7
6
-
93
-
68
70-12
1
69
-
90
7
5
-
99
-11
4
122
-
132
67-94-81-13-EARPH
O
N
E
1
24-119-16-100-89-82-14-EARPH
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E