CIE Abstract

Background
     The quantification of charge was first confirmed  by Robert Millikan in 1909 (which also gave the charge of an electron). This was accomplished through his now-famous oil-drop experiment, in which he used an electric field between a metal plates to balance the force of gravity acting on a charged droplet of oil. This placed that droplet in a state of suspension between the two plates in the electric field. thereby making it's weight, the buoyant force and the product of the electric field and it's charge the only forces acting on it. This made it possible to quantize the charge. A variation of this experiment, which was conducted in the hope of verifying Millikan's original results, is reported here.

Results

     Small nylon balls were used in lieu of the oil used in Millikan's original experiment. These nylon balls were dropped into a metal capacitor that was being charged by a five-thousand volt power source. Rather than floating as the droplets did in the experiment from the early 1900's, the nylon ball fell to the bottom of the capacitor, at which point it was given a charge through the application of air resistance. This caused the ball to accelerate upwards into the higher plate in the capacitor, at which point it remained in contact of that plate. The voltage running through the system was regulated by a potentiometer that can vary by millions of ohms. The distance between the plates and voltage difference were measured to be about 1.0 cm and 1000V/cm respectively. These values were then used to calculate the electric field causing the nylon ball to accelerate toward the top plate. The acceleration of the nylon sphere was determined using a high speed camera. This led to the values of all of the forces acting on the sphere and ultimately the charge of an electron.
     After building the apparatus and taking measurements, the experiment yielded values that were within a reasonable margin of the values that Millikan acquired.

Conclusion

    By imparting an acceleration on the nylon ball it was possible to analyze the electrical forces involved in this acceleration using F(electric)-Mg = Ma with f (electric) being F(electric) = qE. {Having a known E field mass and acceleration, it was possible to determine the charge.} After multiple trials a factor was determined which all the different charges were multiples of, which is the charge of a single electron. This experiment resulted in a values within X% of the accepted value of the charge of an electron, Blah. It was pretty solid.