Today, I will be writing about the type of waves known as Electromagnetic waves.
A Wave is nothing but a disturbance in a medium which occurs due to transfer of energy through the particles in the medium. Waves can be either transverse or longitudinal according to the motion and direction of oscillations. Electromagnetic waves are transverse waves and consist of oscillating electric or magnetic fields. They have a wide range of frequencies and can travel through most media and also through a vacuum.
Electromagnetic waves are everywhere. Quite literally, everywhere. They exist in the deepest corners of space, within galaxies, around star systems, planets and your very own home as well. The Electromagnetic waves include Gamma rays, X rays, Ultraviolet Rays, Visible Light, Infrared Light, Microwaves and Radio waves. All of the above waves are nothing but the propagation of energy through space. Over time, the energy that the wave possesses, decreases and it can transition from one form to another.
Electromagnetic waves have a crest and a trough similiar to ocean waves and the distance between two troughs or two crests is called the wavelength. The number of crests or troughs passing through a specific point in space in one second is known as the frequency of the wave. More the energy carried by the wave, the higher is its frequency and lower its wavelength. All Electromagnetic waves travel at the speed of light. The classification of the Electromagnetic waves can be done on basis of either the wavelength or the frequency.
Gamma Rays : These are the electromagnetic waves emitted by radioactive substances. They have the maximum amount of energy amongst all the waves. The wavelength of gamma waves are around 10^-12 meters long or about the size of an atomic nucleus. The frequency is around 10^24 Hz. Gamma rays can be very harmful to the human body and cause cancer in large doses; but targeted gamma rays can be used to kill the carcinogenic or mutated cells. Gamma rays are also used for irradiating of foods which are susceptible to spoiling by pests.(eg. strawberries)
X Rays : The X rays are electromagnetic waves which ionize gases they pass through, cause phosphorescence or glowing and can bring about chemical changes to photographic plates. X rays can be produced in X ray tubes where sudden obstruction of high velocity electrons produces a high frequency(10^20 Hz), low wavelength (10^-20 m)wave. X rays are commonly used to detect bone fractures as they easily pass through the human flesh but not through the bone. The photograph taken on a special photographic plate shows a high contrast image of the skeletal system.
Ultraviolet Waves : The ultraviolet waves are so named because of their frequency being just greater than the violet colour of visible light. Ultraviolet light is invisible to human sight. The ultraviolet radiation from the sun is what causes the tan when someone sleeps indirect sunlight. UV radiation is fatal to germs,bacteria and lower lifeforms and hence is used in water purification and air handling units. UV radiation is also used to detect forged currency notes which have certain missing features that would be present in actual currency and visible under a UV light source. However, UV radiation has a downside as well; overexposure to UV radiation can cause skin cancer.
Visible Light : The visible light is the only form of the entire electromagnetic spectrum that can be perceived and analysed by the human eye. The visible light is made up of the seven basic colours in the order of “VIBGYOR“(Violet, Indigo, Blue, Green, Yellow, Orange and Red) when arranged in the order of decreasing frequency or increasing wavelength. Visible light causes chemical changes on photographic films. The average wavelength of visible light is about 10^-6 meters or about the size of miniscule bacteria. The colour of any object that we see is because all the other colours of light is absorbed by the object and the observed colour is reflected.
Infrared Light : This is the electromagnetic radiation that is released by hot objects. All objects absorb Infrared Radiation and heat up. Infrared radiation has a wavelength of a millimeter or the size of a pinhead. Infrared radiation detectors are used by the military to detect any hidden enemies as their body constantly gives out heat. Night vision cameras also utilise this property of Infrared light. Infrared light is also used in hand held thermometers which measure the temperature of an object from a distance.
Microwaves : Microwaves are the group of waves having frequencies about 10^8 Hz and wavelengths of about a centimeter or about the size of a dice. The Microwaves are very often used in Radio Detection And Ranging (RADAR) to determine the position of an object by measuring the time it takes to return by hitting the object. Microwaves are also used in Sound Ocean Navigation And Ranging (SONAR) which is basically RADAR for oceanic use. Microwaves are also used in Microwave Ovens for cooking food quickly. This process happens as the water present in the raw food absorbs microwaves and then heats up which leads to faster cooking. However, microwaves are harmful to human cells.
Radiowaves : Radiowaves are the group of waves which have very big wavelengths, often in the range of kilometers. Radiowaves being the largest waves, can travel large distances and hence are used in broadcasting TV and Radio data. Radio waves are the reason your Handheld devices connect to the internet wirelessly : WiFi. Also,GPS units and Mobile signals are transmitted using radiowaves.
The electromagnetic spectrum can also be used to determine the chemical composition of a distant object. More on that in a separate post.
That’s All! Hope you find this info useful!