millikan charge oil drop experiment

Описание: Millikan’s Oil Drop Experiment -
➡️ Introduction
In 1909, Robert A. Millikan and Harvey Fletcher conducted Millikan's Oil Drop Experiment to determine the charge of an electron. The Ryerson Physical Laboratory, which is located at the University of Chicago, was the place where this experiment took place. In addition, this experiment has proven to be incredible in determining the quantum nature of charge.

• Robert A. Millikan, an American physicist, invented a simple method of measuring the minute electric charge that exists on many of the droplets in an oil mist.

• The force on any electric charge in an electric field is equal to the product of the charge and the electric field.

• Millikan was able to determine the magnitude of the charge by measuring both the quantity of electric force and the magnitude of the electric field on the minuscule charge of an isolated oil droplet.

• Robert Millikan was honoured with the Nobel Prize in physics in 1923 for this stunning experiment.

➡️Experiment Procedure
Oil is passed through the atomizer from where it came in the form of tiny droplets. They pass the droplets through the holes present in the upper plate of the apparatus.

The downward motions of droplets are observed through a microscope and the mass of oil droplets, then measure their terminal velocity.

The air inside the chamber is ionized by passing a beam of X-rays through it. The electrical charge on these oil droplets is acquired by collisions with gaseous ions produced by ionization of air.

The electric field is set up between the two plates and so the motion of charged oil droplets can be affected by the electric field.

Gravity attracts the oil in a downward direction and the electric field pushes the charge upward. The strength of the electric field is regulated so that the oil droplet reaches an equilibrium position with gravity.

The charge over the droplet is calculated at equilibrium, which is dependent on the strength of the electric field and mass of droplet.

➡️Balancing Forces:
•Gravity:
Droplets fell due to gravity (weight = mg).
• Electric Force:
An electric field (E) between the plates exerted an upward force (qE) on the charged droplets.
• Equilibrium:
By adjusting the voltage (V) across the plates (E = V/d), Millikan balanced the upward electric force with the downward gravitational force, making the drop float stationary.

➡️Findings & Significance
1. Quantization of Charge:
The calculated charges on the droplets were always integer multiples of a fundamental value (q = ne), demonstrating that charge isn't continuous but comes in discrete packets.

2. Electron Charge:
This fundamental unit was identified as the charge of a single electron, approximately 1.602 x 10^-19 Coulombs (C).

3. Electron Mass:
Combined with J.J. Thomson's charge-to-mass ratio (e/m_e), Millikan's work also helped determine the mass of the electron.