Oil-Drop Experiment
Oil-Drop Experiment
This Demonstration simulates Millikan's well-known oil-drop experiment. By means of a thin nozzle, atomized oil drops are sprayed between two parallel horizontal metal surfaces that form the plates of a capacitor. The drops are ionized using an external x-ray source; statistically, the most likely event is the capture of an electron by the oil drop. However, a drop can also wind up with no charge, a double negative charge or a positive charge. You can see the charges by checking the "show/hide particle charges" box.
If no electric field is present, only gravity acts and all the particles move down at the same speed. The particles are assumed to all have the same mass, which can be calculated from the oil density. Millikan found their volumes using an optical microscope.
If you select the electric field, coulombic electrostatic forces are introduced. You can choose either polarity. The field direction is marked by the + and - symbols on the right. The horizontal lines help you to visualize the motions of the oil drops. [1, 2]