"Light Wave"

Light and sound travels in a medium as a wave. It is very intriguing to dig out information about it and know how it works and how it affect or benefit us, humans. Our technologies today are the main example of how this wave work and benefit us in everyday life. To know more of light wave we should study first what is wave. Wave is undulating motion; a movement through, or over the surface or along the edge of something that is similar in its appearance or effects to a wave.

Waves are divided into types according to the direction of the displacements in relation to the direction of the motion of the wave itself. If the vibration is parallel to the direction of motion, the wave is known as a longitudinal wave. The longitudinal wave is always mechanical because it results from successive compressions (state of maximum density and pressure) and rarefactions (state of minimum density and pressure) of the medium. Sound waves typify this form of wave motion. Another type of wave is the transverse wave, in which the vibrations are at right angles to the direction of motion. A transverse wave may be mechanical, such as the wave projected in a taut string that is subjected to a transverse vibration; or it may be electromagnetic, such as light, X ray, or radio waves. Some mechanical wave motions, such as waves on the surface of a liquid, are combination of both longitudinal and transverse motions, resulting in the circular motion of liquid particles.

 

 LONGITUDINAL WAVE 

   

TRANSVERSE WAVE

For a transverse wave, the wavelength is the distance between two successive crests or troughs. For longitudinal waves, it is the distance from compression to compression or rarefaction to rarefaction. The frequency of the wave is the number of vibrations per second. The velocity of the wave, which is the speed at which it advances, is equal to the wavelength times the frequency. The maximum displacement involved in the vibration is called the amplitude of the wave.

Light wave is an electromagnetic wave which originates in the vibrations of electrons. Light wave has a higher frequency than radio waves but radio waves can be considered as low-frequency light wave. The lowest frequency our eyes can see is perceived by our brain as the color red, and the highest is violet. Still higher frequency is ultraviolet and beyond this are the x-ray and gamma-ray region. In vacuum all waves travel in the same speed but they differ in frequency. The classification of electromagnetic waves according to frequency is the electromagnetic spectrum.

  

 ELECTROMAGNETIC SPECTRUM

Properties of light waves are; diffraction, interference and polarization. Diffraction is property of wave motion, in which waves spread and bend as they pass through small openings or around barriers. Diffraction is more pronounced when the opening, or aperture, or the barrier is similar in size to or smaller than the wavelength of the incoming wave. Diffraction is a property of the motion of all waves. For example, if a radio is turned on in one room, the sound from the radio can be heard in an adjacent room even from around a doorway. Similarly, whenever water waves pass an object on the surface of the water, such as a jetty or boat dock, waves that pass the object's edge spread out into the region behind the object and directly blocked by it.

 

Interference is a property of wave that that occurs when two or more waves overlap or intersect. When waves interfere with each other, the amplitude of the resulting wave depends on the frequencies, relative phases (relative positions of the crests and troughs), and amplitudes of the interfering waves. Interference can occur with all types of waves, not only with light waves. Some of the wavelengths interfere constructively, and other wavelengths interfere destructively. For an instance, we can observe that a bubble appears rainbow colored. It is because of the different wavelengths of light correspond to different colors; the light reflecting off the soap bubble appears colored.

Polarization is another property of wave that the alignment of the transverse electric vectors that make up electromagnetic radiation. Such waves of aligned vibrations are said to be polarized. Polarization is important in wireless communications systems. The physical orientation of a wireless antenna corresponds to the polarization of the radio waves received or transmitted by that antenna. Thus, a vertical antenna receives and emits vertically polarized waves, and a horizontal antenna receives or emits horizontally polarized waves. The best short-range communications is obtained when the transmitting and receiving (source and destination) antennas have the same polarization.

 

See, how amazing waves can be ! ;)