Millikens Oil Drop Experiment
Millikens Oil Drop Experiment
The Millikan Oil Drop Experiment is one of the most popular experiments in undergraduate physics for several reasons.
The experimental principle is straight-forward and easy to understand.
It measures a fundamental atomic constant using a method that won its originator, Robert Millikan, the Nobel Prize.
The observation of the effects of one or more electrons upon oil drops in an electric field provides a striking demonstration of the quantized nature of electricity.
Clear droplet observation and low droplet drift are essential for success with Millikan's classic experiment.
Accuracy in the Oil Drop Experiment depends on the student's ability to accurately measure all the variables involved: plate voltage, plate separation, time and distance of droplet rise and fall, temperature, oil density, etc. Extreme care taken in the design and manufacture of this unit ensures that the student's best efforts will be rewarded with more accurate results.
Minimum Electric Field Distortion--A 0.5 mm diameter droplet entry hole in the top capacitor plate has a negligible effect on the electric field.
Droplet Hole Cover -- Prevents additional droplets from entering the chamber once the experiment has started.
Polished Surfaces -- Polished surfaces on the plate spacer minimize absorption of light (and heat) through the chamber walls.
Electrical Connection -- Electrical connection to the top plate.
Easy Cleaning -- The condenser system easily disassembles for cleaning and inspection
Apparatus of the Milliken's Oil Drop Experiment
The apparatus for the experiment was constructed by Milliken and Fletcher. It incorporated two metal plates held at a distance by an insulated rod. There were four holes in the plate, out of which three were there to allow light to pass through them and one was there to allow viewing through the microscope.
Ordinary oil wasn't used for the experiment as it would evaporate by the heat of the light and so could cause an error in the Millikens Oil Drop Experiment. So, the oil that is generally used in a vacuum apparatus which is of low vapour pressure was used.
