®
Model No. AP-8210A
Equipment
012-13093B
7
Adjusting the height of the platform and leveling it
1.
Place the apparatus on a level, solid table
with the viewing scope at a height that per-
mits the experimenter to sit erect while
observing the droplets through the scope.
One possible setup is to mount the apparatus
on two support rods (ME-8736) on the large
rod stand (ME-8735). See Figure 6.
2.
Using the attached bubble level as a refer-
ence, level the apparatus with the leveling
screws on the rod stand or the leveling feet
on the apparatus (depending on your setup)..
Measuring plate separation
1.
Disassemble the droplet viewing chamber
by lifting the housing straight up and then
removing the upper capacitor plate and the
space plate. (See Figure 5.)
2.
Use a micrometer to measure the thickness of the spacer plate. (The thickness is equal to the plate separation
distance,
d
).
•
Be sure that you are not including the raised rim of the spacer plate in your measurement. The accuracy of this
measurement is important to the degree of accuracy of your experimental results.
3.
Record the measurement.
.
Aligning the Optical System
Focusing the viewing scope
1.
Reassemble the plastic spacer and the upper capacitor
plate onto the lower capacitor plate. Replace the hous-
ing, aligning the holes in its base with the housing pins.
(See Figure 5.)
•
NOTE
: The thorium-232 source and the electrical con-
nection on the lower capacitor plate fit into appropri-
ately sized holes on the plastic spacer.
2.
Unscrew the focusing wire from its storage place on the
platform and carefully insert it into the hole in the center
of the upper capacitor plate (Figure 7.)
3.
Turn the brightness adjustment knob on the light to opti-
mize the contrast between the illuminated pin and the dark background.
Figure 6: Equipment setup
large rod
stand
support
rods
high voltage DC
power supply
adjust to
comfortable eye
level
•
NOTE
: Use care when handling the brass upper capacitor plate and the plastic spacer
plate to avoid scratching them.
•
NOTE
: All surfaces involved in the measurement should be as clean as possible to pre-
vent inaccurate readings.
focusing wire
upper capacitor
plate
lower capacitor
plate
spacer
Figure 7: Focusing wire
