THE DISCOVERY THAT BOUGHT EINSTEIN THE NOBLE PRIZE

We use remote control that triggers TV, AC, etc,. How it works? How the eye's vision is communicated to the brain?
How a bar code reader in a mall works? How the smartphone camera shoots a picture?

"When light waves, infra red rays, ultraviolet falls on certain chemicals like zinc, electrons are ejected out and electric current starts flowing". This process is known as photoelectric effect. It is instantaneous. How can the waves push electron? Can sound waves push an object? No. Can stream of fire disturb a concrete wall? No. So there must be 'something' in the photoelectric effect.

Einstein investigated and proved that light waves sometimes behave like pockets of energy or particles called photons. When one photon strike an atom in a material, one electron is ejected out instantly. It is like throwing a heavy stone on the wall and forcing out one brick. For this discovery he was awarded noble prize.

Now we understand that waves behave like particles. Later people argued, the atomic particles must also behave like waves due to symmetry. So a new science was born.

Photoelectric effect has many natural and artificial applications.

Light image falls on the retina of the eyes and triggers photoelectric effect. The generated current is sent to the brain through nerves and the brain process it. Then we perceive the image and the object.

When the sunlight falls on the plant leaves, the ejected electrons starts the photosynthesis process which is an essential process for the life to sustain on this planet.

When a burglar somehow enters the 'strong room' of a bank, this photoelectric effect starts an alarm. Automatic street lights also works based on this principle.

Long back movie became talkie because of this principle. Voice was converted into electric current then into light and recorded on one side of the film (sound track) . In reproduction the photoelectric effect was used to convert the light into current and then to voice.(today cinema is digitized). So we have so many interesting uses for photoelectric effect.

This effect connects light and electricity; waves and particles; photons and electrons.

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