Light

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TOPIC

LIGHT

INTRODUCTION Light, form of energy visible to the human eye

that is radiated by moving charged particles. Light from the Sun provides the energy needed for plant growth. Plants convert the energy in sunlight into storable chemical form through a process called photosynthesis. Scientists have learned through experimentation that light behaves like a particle at times and like a wave at other times. The particle-like features are called photons.

LIGHT ABSORPTION AND EMISSION When a photon, or packet of light energy, is

absorbed by an atom, the atom gains the energy of the photon, and one of the atom’s electrons may jump to a higher energy level. The atom is then said to be excited. When an electron of an excited atom falls to a lower energy level, the atom may emit the electron’s excess energy in the form of a photon. energy levels orbitals, of the atoms shown here have been greatly simplified to these absorption and emission processes.

SOURCES OF LIGHT

LIGHT AND ELECTROMAGNETIC

RADIATIONDifferent kinds of light are visible to different species. Humans see light in what is called the visible range. It includes all the colors beginning with red and continuing through orange, yellow, green, blue, and violet. Some people can see farther into the violet region or the red region than other people. Some animals have a different sensory range

POLARIZED LIGHTPolarized light consists of individual photons whose electric field vectors are all aligned in the same direction. Ordinary light is unpolarized because the photons are emitted in a random manner, while laser light is polarized because the photons are emitted coherently. When light passes through a polarizing filter, the electric field interacts more strongly with molecules having certain orientations.

LASERLaser, a device that produces and amplifies light. The word laser is an acronym for Light Amplification by Stimulated Emission of Radiation. Laser light is very pure in color, can be extremely intense, and can be directed with great accuracy. Lasers are used in many modern technological devices including bar code readers, compact disc (CD) players, and laser printers

Interference of Light in Bubbles

The different colors that appear to streak the surface of soap bubbles correspond to different wavelengths of visible light interfering with each other at that point on the bubble’s surface.

Separation of White Light into Colored Light

Light from many sources, such as the Sun, appears white. When white light passes through a prism, however, it separates into a spectrum of different colors. The prism separates the light by refracting, or bending, light of different colors at different angles.

Refraction of LightRefraction is the bending of a light ray as it

passes from one substance to another. The light ray bends at an angle that depends on the difference between the speed of light in one substance and the next. Sunlight reflecting off a fish in water, for instance, changes to a higher speed and bends when it enters air. The light appears to originate from a place in the water above the fish’s actual position.

Diffraction and Interference of Light

when light passes through a slit with a size that is close to the light’s wavelength, the light will diffract, or spread out in waves. when light passes through two slits, the waves from one slit will interefere with the waves from the other. constructive interference occurs when a wavefront, or crest, from one wave coincides with a wavefront from another, forming a wave with a larger crest.

mirrorMirror, optical device, commonly made of glass, with a smooth, polished surface that forms images by the reflection of rays of light Mirrors made of brass are mentioned in the Bible, and mirrors of bronze were in common use among the ancient Egyptians, Greeks, and Romans

Human eyeEye, light-sensitive organ of vision in animals. The eyes of various species vary from simple structures that are capable only of differentiating between light and dark to complex organs, such as those of humans and other mammals, that can distinguish minute variations of shape, color, brightness, and distance..

Speed of lightInformation he calculated that the speed of light in air was 194,000 miles per second. Later investigators refined this method. Jean Foucault replaced the disk with rotating mirrors and arrived at a value of 186,000 miles per second.

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DONE BY:- E.SAI KIRAN