Question

In the Millikan’s Oil Drop experiment, the oil drop is subjected to such forces whose nature does NOT fall under the category of:
1. electrostatic
2. gravitational
3. viscous
4. magnetostatic

Answer 1

Correct Answer - Option 4 : magnetostatic

The correct answer is magnetostatic.

•  In 1913, the American physicist R. A. Millikan performed the pioneering oil-drop experiment for the precise measurement of the charge on an electron. He found that the charge on an oil-droplet was always an integral multiple of an elementary charge, 1.602 × 10^-19 C. Millikan’s experiment established that electric charge is quantized. From the values of charge (e) and specific charge(e/m ), the mass (m) of the electron could be determined.
• In the experiment a tiny charged droplets of oil was suspended between two metal electrodes. The pull of downward gravitational force was balanced with the help of upward drag and electric forces. The density of the oil, electric field and mass was known, with the help of these known parameter, Millikan determined the charge on oil droplets in mechanical equilibrium.