Jumat, 14 Januari 2011
Creeping wave is a vibration. Ideal shape of a wave will follow the motion sinusoide. Apart from electromagnetic radiation, and possibly gravitational radiation, which can run through a vacuum, there are also on medium wave (which is due to change in form can produce restoring forces which flexure) where they can walk and can transfer energy from one place to another without causing particle medium migrate permanently, ie no mass displacement. In fact, every special point oscillates around a certain position.
A medium is called:
linear if the waves are different in every particular point in the medium can be summed,
limited, if limited, but it is called infinite
uniform if its physical characteristics do not change at different points
isotropic if the physical characteristics of the "same" in different directions
Electromagnetic waves are waves that can propagate though no medium. Propagate in a wave of electromagnetic energy with a few characters that can be measured, namely: wavelength / wavelength, frequency, amplitude / amplitude, velocity. Amplitude is the height of the wave, while the wavelength is the distance between two peaks. Frequency is the number of waves passing through a point in one unit of time. Frequency depends on the speed of the wave vine. Because the electromagnetic energy is a constant speed (the speed of light), wavelength and frequency is inversely proportional. The longer a wave, the lower the frequency, and the shorter the wave the higher frequencies.
Electromagnetic energy emitted, or released, by all the time in the universe at a level different. Higher levels of energy in an energy source, the lower the wavelength of the energy produced, and the higher frequency. Different characteristics of the wave energy is used to classify electromagnetic energy.
The characteristics of electromagnetic waves:
From the description above can conclude several characteristics of electromagnetic waves is as follows:
1. Changes in the electric field and magnetic field occurs at the same time, so that the two fields have a maximum and minimum prices at the same time and at the same place.
2. The direction of electric field and magnetic field perpendicular to each other and both perpendicular to the direction of wave propagation.
3. From the characteristics of No. 2 showed that electromagnetic waves are transverse waves.
4. Like the waves in general, an incident electromagnetic wave reflection, refraction, interference, and diffraction. Also experienced a polarization event because it included a transverse wave.
5. Fast propagation of electromagnetic waves depends only on the electrical properties and the magnetic medium by which this occurred.
Light visible to the eye is not only the type that allows electromagnetic radiation. Opinions James Clerk Maxwell showed that electromagnetic waves other, in contrast to visible light by the eye in his wavelength and frequency, could have been there. These theoretical conclusions were remarkably reinforced by the Heinrich Hertz, who could produce and meet the two waves are visible by eye was predicted by Maxwell. A few years later Guglielmo Marconi demonstrates that the wave of the invisible eye that can be used for communication without wires, so what was his name is radio. Now, we use also for television, x-rays, gamma rays, infrared rays, ultraviolet rays are examples of electromagnetic radiation. Everything can be learned through the ideas of Maxwell.
SOURCE electromagnetic waves
sunlight produces infrared rays.
mercury lamp produces ultra violet.
The shooting of electrons in vacuum tubes on the metal pieces produce X-rays (used for x-rays).
Unstable nuclei produce gamma rays.
SPECTRUM electromagnetic waves
The composition of all forms of electromagnetic waves based on wavelengths and frequencies called the electromagnetic spectrum. Image of the electromagnetic spectrum below have been prepared on the wavelength (measured in units _m) includes a very low energy range, with wavelengths of high and low frequencies, like radio waves to very high energy, with a low wavelength and high frequency radiation such as X -ray and Gamma Ray.
Examples of the electromagnetic spectrum
Radio waves are classified according to wavelength or frequency. If the wavelength is high, then definitely a low frequency or vice versa. The frequency of radio waves from 30 kHz up and grouped according to broad bands. The radio waves generated by electric charges are accelerated through conductive wires. These charges are generated by electronic circuit called the oscillator. These radio waves emitted from the antenna and received by the antenna as well. You can not hear the radio directly, but the radio receiver will change the first wave energy into sound energy.
Microwaves (mikrowaves) is a radio wave with the highest frequency that is above 3 GHz. If the microwaves are absorbed by an object, it would appear that the warming effect on the body. If the food absorb microwave radiation, then the food becomes hot in a very short time interval. The process is utilized in a microwave oven to cook food quickly and economically.
Microwaves are also used in aircraft RADAR (Radio Detection and Ranging) RADAR means finding and determine the trace of an object using microwaves. Aircraft radar utilizing the reflection properties of microwaves. Because the velocity of electromagnetic wave c = 3 X 108 m / s, then by observing the time interval between transmitting the reception.
Infrared rays covering area up to 1014 Hz 1011Hz frequency or wavelength region 10-4 cm to 10-1 cm. if you check the spectrum produced by an incandescent lamp with a detector which is connected to the miliampermeter, then the needle ampermeter slightly above the tip of the red spectrum. Light rays are not visible but can be detected in the upper red spectrum is called infrared radiation.
Infrared rays produced by electrons in the molecules vibrate as Theys That in heat. So Would any hot objects emit infrared light. The amount of infrared light emitted Depends on temperature and color of objects.
Visible light as electromagnetic radiation most familiar to us can be defined as part of the electromagnetic wave spectrum that can be detected by human eye. The wavelength depends on the color looks nervariasi wavelengths ranging from approximately 4 x 10-7 m to light violet (purple) to 7x 10-7 m for a red light. Usefulness of light one of them go round the use of lasers in optical fiber for telecommunications and medical.
Ultraviolet light has a frequency of 1015 Hz in the region until 1016 Hz or in a long region wave 10-8 m 10-7 m. these waves are generated by atoms and molecules in electric flame. The sun is a major source that emits ultraviolet rays on the surface of the earth, the ozone layer is in the top layer that serves atmosfer absorb ultraviolet rays and ultraviolet rays forward that does not endanger the lives of living beings on earth.
X-rays have a frequency between 10 Hz to 10 Hz. very short wavelength of 10 cm to 10 cm. although such an X-ray but has strong penetrating power, can penetrate thick books, wood several inches thick and 1 cm thick aluminum plate.
Gamma rays have a frequency between 10 Hz to 10 Hz or a wavelength of between 10 cm to 10 cm. Greatest penetrating power, which causes serious effects when absorbed by body tissue.
Examples of the application of electromagnetic waves in everyday life:
Radio energy is the lowest form of electromagnetic energy levels, with a range of wavelengths from thousands of kilometers to less than one meter. The use of most of the communication, to investigate outer space and radar systems. Radar is useful to study the weather patterns, storms, making the 3D map of the earth's surface, measure rainfall, movement of ice in the polar region and monitor the environment. Radar wavelength range between 0.8 - 100 cm.
Microwave radiation wavelength range between 0.3 - 300 cm. Its use is mainly in the fields of communication and information delivery through open space, cooking, and PJ system active. In PJ active system, a microwave pulse is fired through a target and its reflection was measured to study the characteristics of the target. As an application example is the Tropical Rainfall Measuring Mission's (TRMM) Microwave Imager (TMI), which measures the microwave radiation emitted from the electromagnetic spectrum Electromagnetic energy of the earth's atmosphere to measure evaporation, water content in clouds and rain intensity.
Health conditions can be diagnosed by investigating the infrared emission from the body. Special infrared photo called thermogram is used to detect blood circulation problems, arthritis and cancer. Infrared radiation can also be used in burglar alarms. A thief without his knowledge will impede the light and hide the alarm. Communicate with the TV remote control via infrared radiation generated by the LED (Light Emitting Diode) contained within the unit, so that we can turn on the TV from a distance with a remote control.
UV light is needed in the assimilation of plants and can kill the germs in the skin.
X-rays are commonly used in the medical field to photograph the position of the bones in the body especially to determine a broken bone. However, the use of X-rays have to be careful because the network of human cells can be damaged by use of X-rays that are too long.