Question

What did Millikan’s oil drop element reveal about the nature of electric charge?

Answer 1

Hint: When the matter is put in an electromagnetic field, it acquires an electric charge, which causes it to undergo a force. Positive and negative charges are the two forms of electric charge (commonly carried by protons and electrons respectively)

Complete answer:
Millikan's oil-drop experiment was the first direct and convincing calculation of a single electron's electric charge. The experiment was first carried out in $1909$ by American physicist Robert A. Millikan, who invented a simple method of calculating the minute electric charge present on many of the droplets in an oil mist. The product of the charge and the electric field equals the force on any electric charge in an electric field. Millikan was able to calculate the magnitude of the charge by measuring both the sum of electric force and the magnitude of the electric field on the tiny charge of an isolated oil droplet.

He was able to calculate the electric charge on each drop by relating applied electric force to shifts in the motion of the oil drops. He discovered that the charges on all of the drops were simple multiples of a single number, the electron's fundamental charge.

There was also a lot of controversy about whether electric charging was continuous or not at the time. Millikan was convinced that the smallest unit of charge existed and set out to prove it. The oil drop experiment yielded a significant result. The oil drop experiment by Millikan demonstrated that electric charge can be quantified.

This was secondary winning that he was successful in determining the size of the electron.

Note: They confirmed that the charges were all small integer multiples of a certain base value, which was found to be $$1.5924\left(17\right)\times {10}^{-19}C$$, about $0.6$ percent different from the currently accepted value of $$1.602176634\times {10}^{-19}C$$, by repeating the experiment for many droplets.