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.

Comments

LISSAJOUS FIGURES

Definition: "When a particle is subjected to two sine wave motion or two oscillatory motion at right angles, the particle describes lissajous figures". We know sine wave motion and circular motion is basically same. Hence we draw two circles A and B perpendicular to each other. The circle B rotates twice faster than circle A. That is, frequency of circle B is two times than that of A. A particle at the intersection of two circles is subjected to two sine wave motion A and B at 90 degree simultaneously. The particle will describe figures depending on the frequency and phase of A and B . In our case, the ratio of frequency is 1:2 and the two waves are in phase. To draw lissajous figures : A moving point in both the circles are chosen. Here we should remember; during the time taken by the circle A to complete one rotation, circle B completes two. Hence the points are marked on the circles according to their speed. Then straight lines

THE PARABOLA

A jet of water shooting from a hose pipe will follow a parabolic path. What is the so special about parabola. Y= x^2 Draw a graph for the above equation. It will result in a parabola. This parabola is also called unit parabola. Any equation involving square will yield a parabola. Example: Y = 2x^2 +3x+3 (also called quadratic equation) X= 2 and -2, both satisfies the equation 4 = X^2. Parabolic equations always have two solutions. Any motion taking place freely under gravity follows parabolic path. Examples: An object dropped from a moving train, A bomb dropped from flying plane, A ball kicked upwards. If a beam of light rays fall on the parabolic shaped mirror, they will be reflected and brought to focus on a point. This fact is made use of in Dish Antenna, Telescope mirrors, etc. Inverted parabola shape is used in the construction of buildings and bridges. Because the shape is able to bear more weight. A plane

CASINO'S GAME

Let us find out how the casino survives with mathematics. Say, your friend invite you for a game of dice. You must bet (wager) 2 dollars. If you roll 'six' you will get back 8 dollars. The game will go on for 30 rounds. All sounds good. The probability of rolling 'six' is 1/6. Since the game will be played for 30 times, the 'expected win' is 30*1/6 = 5. That is, you are expected to win 5 rounds out of 30. Hence your gain will be 5 * 8 =40 dollars. ok. This also implies that you will loose 25 rounds. Hence your loss will be 25*2 =50 dollars. Your net gain will be gain-less = 40-50 = -10 dollars. For 30 rounds, the loss is -10 dollars, Hence, for one round =-10/30 = -1/3 dollars. There will be a loss of -1/3 or 0.33 dollars per round. It is not a fair game. Let us make a simple formula to calculate 'Pay out per round\. The probability for a win = p The pay-out in case of win = V No. of rounds = n The expect

sciencecapsules

Search This Blog