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M o d e l N o . A P - 8 2 1 0 A
Determining the Temperature of the Droplet Viewing Chamber
1.
Connect the multi meter to the thermistor connectors on the platform in order to measure the resistance of the
thermistor that is embedded in the lower capacitor plate.
2.
Refer to the Thermistor Resistance Table located on the platform to find the temperature of the lower brass
plate. The measured temperature corresponds to the temperature inside the droplet viewing chamber.
.
The temperature inside the droplet viewing chamber should be determined periodically
(about every fifteen minutes).
Experimental Procedure
1.
Complete the reassembly of the droplet viewing chamber by placing the droplet hole cover on the upper
capacitor plate and then placing the lid on the housing. (See Figure 5.)
•
NOTE: The droplet hole cover has a hole in one side and a hole in the bottom. The hole in the bottom lines up
with the small hole in the center of the upper capacitor plate.
•
NOTE: The droplet hole cover prevents additional droplets from entering the chamber once the experiment
has started.
2.
Measure and record the plate voltage and the thermistor resistance (temperature).
Introducing the droplets into the chamber
1.
Put non-volatile oil of known density into the atomizer, such as the included Squibb #5587 Mineral Oil, den-
3
sity of 886 kg/m
.
2.
Insure that the tip of the atomizer is pointed down (90° to the shaft; see Fig-
ure 9). Prepare the atomizer by rapidly squeezing the bulb until oil is spray-
ing out.
3.
Move the ionization source lever to the "Spray Droplet Position" to allow
air to escape from the chamber during the introduction of droplets into the
chamber.
4.
Place the tip of the atomizer into the hole on the lid of the droplet viewing
chamber.
5.
While observing through the viewing scope, squeeze the atomizer bulb with one quick squeeze. Then squeeze
it slowly to force the droplets through the hole in the droplet hole cover, through the droplet entry hole in the
upper capacitor plate, and into the viewing area space between the two capacitor plates.
6.
When you see a shower of drops through the viewing scope, move the ionization source lever to the 'OFF'
position.
.
If repeated "squirts" of the atomizer fail to produce any droplets in the viewing area
but produce a rather cloudy brightening of the field of view, the hole in the upper
capacitor plate or in the droplet hole cover may be clogged. Refer to the Maintenance
section for cleaning instructions.
•
NOTE: The exact technique of introducing droplets will need to be developed by the experimenter. The
object is to get a small number of drops, not a large, bright cloud from which a single drop can be chosen.
®
0 1 2 - 1 3 0 9 3 B
E q u i p m e n t
shaft
tip
droplets
Figure 9: Atomizer tip
9
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