Millikan Oil Drop Apparatus
Equipment
®
6
012-13093B
•
thermistor connectors, 4 mm diameter (the thermistor is mounted in the lower capacitor plate in the droplet
viewing chamber)
.
•
thermistor resistance table (resistance versus temperature)
•
ionization source lever with three positions: Ionization ON, Ionization OFF, and Spray Droplet Position.
•
bubble level
•
support rod mounts and screws to permit mounting of the platform on support rods (so the viewing scope can
be raised to a comfortable eye level)
•
leveling feet (3)
•
plate charging switch on a one meter cord (to prevent vibration of the platform during the switching activity).
Components of the Droplet Viewing Chamber
•
lid (chamber cover)
•
housing
•
convex lens (not shown)
.
•
upper capacitor plate (brass)
•
plastic spacer (approximately 7.6 mm thick)
•
lower capacitor plate (brass)
•
alpha source, thorium-232, 0.00185 microcurie
•
electrical connection to the upper capacitor plate
Note
: Thorium-232 is a naturally occurring, low level
alpha-particle emitter with a half-life of 1.41 x 10
10
years. It is
not regulated in its use and poses no hazard to the user of the
PASCO Millikan Oil Drop Apparatus..
Equipment Setup
Adjusting the environment of the experiment room
1.
Make the room as dark as possible, while allowing for
adequate light to read the multi meter and stopwatch and
to record data.
2.
Insure that the background behind the apparatus is dark.
3.
Select a location that is free of drafts and vibrations.
WARNING: Do not apply voltage to the thermistor connectors!
lid
housing
droplet hole
cover
upper
capacitor
plate
spacer
lower
capacitor
plate
thorium-232
electrical
connector
housing
pins
base of
apparatus
Figure 5: Droplet viewing chamber