ELECTROMAGNETIC WAVE
Electromagnetic waves which are formulated by Maxwell was stretched in a wide frequency range. As a wave phenomena, electromagnetic waves can be identified by frequency and wavelength. Light is electromagnetic waves as radio waves or X-rays. Each has a different use of the physics even though they describe a similar phenomenon, namely the wave phenomena, more specifically electromagnetic waves. They are distinguished by frequency and wavelength. The following figure shows the spectrum of electromagnetic waves.
Electromagnetic wave spectrum
Radio waves
Of course you often watch TV, listen to the radio, or using mobile phones to communicate, right? Well, all electronic devices that use radio waves as the signal propagation.
man-on-phoneGelombang radio is a wave that has the smallest frequency or longest wavelength. Radio waves within a wide frequency range covering a few Hz to gigahertz (GHz or order of rank 9). These waves are generated by electronic devices in the form of an oscillator circuit (a combination of component variation and resistors (R), inductors (L) and capacitor (C)). Therefore, radio waves are widely used in telecommunication systems. Broadcast TV, radio, and cellular telephone networks use radio waves in this wave range.
A telecommunications system that uses radio waves as a signal carrier information basically consists of a transmitter antenna and receiver antenna. Before dirambatkan as radio waves, the signal information in various forms (the voice on the radio systems, voice and data in cellular systems, or sounds and images on the TV system) first modulated. Modulation here is simply stated as a merger between electric vibration information (eg voice on the radio system) with the radio frequency carrier wave. This merging produces a radio wave modulated. These waves dirambatkan through space from transmitter to receiver.
Therefore, we know of the terms AM and FM. Amplitude modulation (AM) or amplitude modulation combines the power of vibration and the vibration amplitude changes bearer form. The frequency modulation (FM) or frequency modulation combines the power of vibration and vibration frequency of the carrier in the form of change.
Microwave
microwave ovens
Have you ever heard of an electronic device such as a microwave oven? Or, you may have used it for cooking? Microwave ovens use microwave properties (microwave) effects in the form of heat for cooking. In addition, microwaves are also used in radar and communications systems analysis of the structure of atoms and molecules.
Microwave frequency range extending from 3 GHz to 300 GHz. The frequency of this generated from oscillator circuits in electronic devices. Microwaves can be absorbed by an object and the heating effect on the object. A microwave-based heating systems can take advantage of this phenomenon is to cook it. Such systems are used in a microwave oven that can cook food in it evenly and in a short time (fast).
In a system of radar, microwaves emitted continuously in all directions by the transmitter. If any objects affected by this wave, the signal will be reflected by the object and received back by the recipient. This reflected signal will provide information that there was a near object to be displayed by the radar screen.
scanner
From time to transmitting signals received by the radar, the distance of the detected object can be known. Of course you can imagine a formula that can be used to calculate this distance, is not it? Yes, the distance is speed multiplied by time, and because the wave velocity is constant, then by knowing the time, distance can be calculated. Do not forget that the division by a factor of two is necessary because the signal distance commute. Please you write down the formula.
Radar systems used by aircraft and submarines. With the radar, aircraft and submarines capable of detecting the presence of other objects close to them. When bad weather where there are storms and weather disturbances that can interfere with vision, the presence of radar to help navigate the aircraft to determine their direction and position of the landing destination.
Infrared Rays
How the TV remote can be used to turn off or turn on the TV? Here the remote uses infrared light transmitter and receiver. Did you know that there are mobile phones equipped with infrared to transfer data from or to a mobile phone?
Infrared light (infrared / IR) included in the electromagnetic wave and in the frequency range 300 GHz to 40,000 GHz (10 ^ 13). Infrared rays generated by the process in the molecule and a hot body. It has long been known that a hot body due to activity (vibration) in which atomic and molecular considered to radiate heat wave in the form of infrared rays. Therefore, the infrared light is often called heat radiation.
Photo infrared radiant heat that works on the basis of an object can be used to make paintings of heat from an area or object. Hot paintings may depict the results of which area is hot and not. A painting of heat from one building can be used to determine which areas of the building that generate excessive heat that can be done the necessary repairs.
In the health field, radiant heat in the form of infrared rays of the organs can be used as information on health conditions of these organs. This is very useful for physicians in the diagnosis and make decisions appropriate action patients. In addition, radiant heat in a certain intensity are believed to be used for the healing process of diseases such as smallpox, and gout.
results of an infrared photograph images of the human body for medical examination
In electronic technology, infrared rays have long been used as a medium of data transfer. Mobile phones and laptops equipped with infrared connectivity as one to connect or transfer data from one device to another device. Infrared function on cell phones and laptops run through IrDa technology (infra-red data acquitition).
Light or visible light
In the spectral range of electromagnetic waves, light or visible light occupies only a narrow band above the infrared light. Visible light frequency spectrum contains the frequency at which the human eye is sensitive to it. The frequency of visible light, extending between 40 000 and 80 000 GHz (10 ^ 13) or correspond with wavelengths between 380 and 780 nm (10 -9). Light that we feel everyday in this frequency range. Light is also produced through the process in the scale of atoms and molecules in the form of internal settings in the configuration of electrons.
A discussion of the light was so extensive and formed a separate disciplines of physics, namely optics.
Ultraviolet Rays
Frequency range of ultraviolet light (ultraviolet) stretches in the range 80 000 GHz to tens of millions GHz (10 ^ 17).
Ultraviolet rays or ultraviolet rays is also coming from solar ultraviolet radiation has an energy that is strong enough and able to ionize the atoms in the layer of the atmosphere. From the process of ionization of atoms is generated ions, which are electrically charged atoms. Layers consisting of these ions to form a special layer in the atmosphere called the ionosphere. Layer of the ionosphere that are filled with electrically charged atoms can reflect electromagnetic waves of low frequency (within a frequency spectrum of radio waves of medium) and used in radio transmissions.
Because of his energy and strong enough in character that can ionize the material, ultraviolet radiation, which is classified as hazardous to humans (particularly if emitted in large intensity). Fortunately, the Earth's atmosphere has a layer that can withstand and absorb ultraviolet radiation from the sun so that sunlight reaching the earth is in a harmless level. Of course you already know the layer that is? yes, the ozone layer.
ozone layer in the atmosphere to hold some ultraviolet radiation
Use of chemicals for cooling (refrigerators and air conditioning) or to the freon in the form of a spray (spray and perfume form pilok / spray paint), may cause leakage of the ozone layer. This causes the ultraviolet rays can penetrate the ozone layer and to the earth's surface, something that is very dangerous for humans. If more and more exposed to ultraviolet light onto the surface of the earth and of humans, adverse effects to humans and the environment can be incurred.
causing gas to spray the hole in the ozone layer
Skin cancer and vision problems, diseases such as cataracts can be caused from excessive ultraviolet radiation. Green algae as a source of natural food and the first chain in the food chain may decrease as a result of this ultraviolet radiation. This can disrupt the balance of nature and is something that is very harmful for the life of living creatures on Earth.
Ultraviolet rays can also be generated by internal processes of atoms and molecules. Ultraviolet rays can also be used in food sterilization process in which germs and harmful bacteria in food can be turned off.
X-ray
X-rays in medicine known as X-rays. Used to examine internal organs in the body. Fracture on the inside of the body can be seen using this X-ray.
X-rays are at 300 million GHz frequency range (10 ^ 17) and 50 billion GHz (10 ^ 19). The discovery of X-rays are considered as one of the important discoveries in physics. X-rays discovered by German physicist named Wilhelm Rontgen when he was studying cathode rays. The most common way to produce X-rays is through a mechanism called radiation bremstrahlung or deceleration. This mechanism is implemented by the X-ray the first time to produce X-rays. In the theory of electromagnetic wave radiation is known that electric charge is accelerated (or slowed) would produce electromagnetic waves. Furthermore through deceleration radiation, X-rays are also produced from the internal transition process of electrons in atoms or molecules.
photo results of X-ray irradiation
Gamma Rays
production of gamma rays by atomic nuclei
Gamma rays are electromagnetic waves having a frequency (and hence energy) is greatest. Gamma rays have a frequency range from 18 to 10 rank 10 rank 22 Hz. Gamma rays produced through the processes within the nucleus (nuclear).
Electromagnetic waves which are formulated by Maxwell was stretched in a wide frequency range. As a wave phenomena, electromagnetic waves can be identified by frequency and wavelength. Light is electromagnetic waves as radio waves or X-rays. Each has a different use of the physics even though they describe a similar phenomenon, namely the wave phenomena, more specifically electromagnetic waves. They are distinguished by frequency and wavelength. The following figure shows the spectrum of electromagnetic waves.
Electromagnetic wave spectrum
Radio waves
Of course you often watch TV, listen to the radio, or using mobile phones to communicate, right? Well, all electronic devices that use radio waves as the signal propagation.
man-on-phoneGelombang radio is a wave that has the smallest frequency or longest wavelength. Radio waves within a wide frequency range covering a few Hz to gigahertz (GHz or order of rank 9). These waves are generated by electronic devices in the form of an oscillator circuit (a combination of component variation and resistors (R), inductors (L) and capacitor (C)). Therefore, radio waves are widely used in telecommunication systems. Broadcast TV, radio, and cellular telephone networks use radio waves in this wave range.
A telecommunications system that uses radio waves as a signal carrier information basically consists of a transmitter antenna and receiver antenna. Before dirambatkan as radio waves, the signal information in various forms (the voice on the radio systems, voice and data in cellular systems, or sounds and images on the TV system) first modulated. Modulation here is simply stated as a merger between electric vibration information (eg voice on the radio system) with the radio frequency carrier wave. This merging produces a radio wave modulated. These waves dirambatkan through space from transmitter to receiver.
Therefore, we know of the terms AM and FM. Amplitude modulation (AM) or amplitude modulation combines the power of vibration and the vibration amplitude changes bearer form. The frequency modulation (FM) or frequency modulation combines the power of vibration and vibration frequency of the carrier in the form of change.
Microwave
microwave ovens
Have you ever heard of an electronic device such as a microwave oven? Or, you may have used it for cooking? Microwave ovens use microwave properties (microwave) effects in the form of heat for cooking. In addition, microwaves are also used in radar and communications systems analysis of the structure of atoms and molecules.
Microwave frequency range extending from 3 GHz to 300 GHz. The frequency of this generated from oscillator circuits in electronic devices. Microwaves can be absorbed by an object and the heating effect on the object. A microwave-based heating systems can take advantage of this phenomenon is to cook it. Such systems are used in a microwave oven that can cook food in it evenly and in a short time (fast).
In a system of radar, microwaves emitted continuously in all directions by the transmitter. If any objects affected by this wave, the signal will be reflected by the object and received back by the recipient. This reflected signal will provide information that there was a near object to be displayed by the radar screen.
scanner
From time to transmitting signals received by the radar, the distance of the detected object can be known. Of course you can imagine a formula that can be used to calculate this distance, is not it? Yes, the distance is speed multiplied by time, and because the wave velocity is constant, then by knowing the time, distance can be calculated. Do not forget that the division by a factor of two is necessary because the signal distance commute. Please you write down the formula.
Radar systems used by aircraft and submarines. With the radar, aircraft and submarines capable of detecting the presence of other objects close to them. When bad weather where there are storms and weather disturbances that can interfere with vision, the presence of radar to help navigate the aircraft to determine their direction and position of the landing destination.
Infrared Rays
How the TV remote can be used to turn off or turn on the TV? Here the remote uses infrared light transmitter and receiver. Did you know that there are mobile phones equipped with infrared to transfer data from or to a mobile phone?
Infrared light (infrared / IR) included in the electromagnetic wave and in the frequency range 300 GHz to 40,000 GHz (10 ^ 13). Infrared rays generated by the process in the molecule and a hot body. It has long been known that a hot body due to activity (vibration) in which atomic and molecular considered to radiate heat wave in the form of infrared rays. Therefore, the infrared light is often called heat radiation.
Photo infrared radiant heat that works on the basis of an object can be used to make paintings of heat from an area or object. Hot paintings may depict the results of which area is hot and not. A painting of heat from one building can be used to determine which areas of the building that generate excessive heat that can be done the necessary repairs.
In the health field, radiant heat in the form of infrared rays of the organs can be used as information on health conditions of these organs. This is very useful for physicians in the diagnosis and make decisions appropriate action patients. In addition, radiant heat in a certain intensity are believed to be used for the healing process of diseases such as smallpox, and gout.
results of an infrared photograph images of the human body for medical examination
In electronic technology, infrared rays have long been used as a medium of data transfer. Mobile phones and laptops equipped with infrared connectivity as one to connect or transfer data from one device to another device. Infrared function on cell phones and laptops run through IrDa technology (infra-red data acquitition).
Light or visible light
In the spectral range of electromagnetic waves, light or visible light occupies only a narrow band above the infrared light. Visible light frequency spectrum contains the frequency at which the human eye is sensitive to it. The frequency of visible light, extending between 40 000 and 80 000 GHz (10 ^ 13) or correspond with wavelengths between 380 and 780 nm (10 -9). Light that we feel everyday in this frequency range. Light is also produced through the process in the scale of atoms and molecules in the form of internal settings in the configuration of electrons.
A discussion of the light was so extensive and formed a separate disciplines of physics, namely optics.
Ultraviolet Rays
Frequency range of ultraviolet light (ultraviolet) stretches in the range 80 000 GHz to tens of millions GHz (10 ^ 17).
Ultraviolet rays or ultraviolet rays is also coming from solar ultraviolet radiation has an energy that is strong enough and able to ionize the atoms in the layer of the atmosphere. From the process of ionization of atoms is generated ions, which are electrically charged atoms. Layers consisting of these ions to form a special layer in the atmosphere called the ionosphere. Layer of the ionosphere that are filled with electrically charged atoms can reflect electromagnetic waves of low frequency (within a frequency spectrum of radio waves of medium) and used in radio transmissions.
Because of his energy and strong enough in character that can ionize the material, ultraviolet radiation, which is classified as hazardous to humans (particularly if emitted in large intensity). Fortunately, the Earth's atmosphere has a layer that can withstand and absorb ultraviolet radiation from the sun so that sunlight reaching the earth is in a harmless level. Of course you already know the layer that is? yes, the ozone layer.
ozone layer in the atmosphere to hold some ultraviolet radiation
Use of chemicals for cooling (refrigerators and air conditioning) or to the freon in the form of a spray (spray and perfume form pilok / spray paint), may cause leakage of the ozone layer. This causes the ultraviolet rays can penetrate the ozone layer and to the earth's surface, something that is very dangerous for humans. If more and more exposed to ultraviolet light onto the surface of the earth and of humans, adverse effects to humans and the environment can be incurred.
causing gas to spray the hole in the ozone layer
Skin cancer and vision problems, diseases such as cataracts can be caused from excessive ultraviolet radiation. Green algae as a source of natural food and the first chain in the food chain may decrease as a result of this ultraviolet radiation. This can disrupt the balance of nature and is something that is very harmful for the life of living creatures on Earth.
Ultraviolet rays can also be generated by internal processes of atoms and molecules. Ultraviolet rays can also be used in food sterilization process in which germs and harmful bacteria in food can be turned off.
X-ray
X-rays in medicine known as X-rays. Used to examine internal organs in the body. Fracture on the inside of the body can be seen using this X-ray.
X-rays are at 300 million GHz frequency range (10 ^ 17) and 50 billion GHz (10 ^ 19). The discovery of X-rays are considered as one of the important discoveries in physics. X-rays discovered by German physicist named Wilhelm Rontgen when he was studying cathode rays. The most common way to produce X-rays is through a mechanism called radiation bremstrahlung or deceleration. This mechanism is implemented by the X-ray the first time to produce X-rays. In the theory of electromagnetic wave radiation is known that electric charge is accelerated (or slowed) would produce electromagnetic waves. Furthermore through deceleration radiation, X-rays are also produced from the internal transition process of electrons in atoms or molecules.
photo results of X-ray irradiation
Gamma Rays
production of gamma rays by atomic nuclei
Gamma rays are electromagnetic waves having a frequency (and hence energy) is greatest. Gamma rays have a frequency range from 18 to 10 rank 10 rank 22 Hz. Gamma rays produced through the processes within the nucleus (nuclear).
GELOMBANG ELEKTROMAGNETIK
SPEKTRUM GELOMBANG ELEKTROMAGNETIK
Gelombang elektromagnetik yang dirumuskan oleh Maxwell ternyata terbentang dalam rentang frekuensi yang luas. Sebagai sebuah gejala gelombang, gelombang elektromagnetik dapat diidentifikasi berdasarkan frekuensi dan panjang gelombangnya. Cahaya merupakan gelombang elektromagnetik sebagaimana gelombang radio atau sinar-X. Masing-masing memiliki penggunaan yang berbeda meskipun mereka secara fisika menggambarkan gejala yang serupa, yaitu gejala gelombang, lebih khusus lagi gelombang elektromagnetik. Mereka dibedakan berdasarkan frekuensi dan panjang gelombangnya. Gambar berikut ini menunjukkan spektrum gelombang elektromagnetik.
spektrum gelombang elektromagnetik
Gelombang Radio
Tentu kamu sering menonton TV, mendengarkan radio, atau menggunakan ponsel untuk berkomunikasi, bukan? Nah, semua peralatan elektronik itu menggunakan gelombang radio sebagai perambatan sinyalnya.
Gelombang radio merupakan gelombang yang memiliki frekuensi paling kecil atau panjang gelombang paling panjang. Gelombang radio berada dalam rentang frekuensi yang luas meliputi beberapa Hz sampai gigahertz (GHz atau orde pangkat 9). Gelombang ini dihasilkan oleh alat-alat elektronik berupa rangkaian osilator (variasi dan gabungan dari komponen Resistor (R), induktor (L), dan kapasitor (C)). Oleh karena itu, gelombang radio banyak digunakan dalam sistem telekomunikasi. Siaran TV, radio, dan jaringan telepon seluler menggunakan gelombang dalam rentang gelombang radio ini.Suatu sistem telekomunikasi yang menggunakan gelombang radio sebagai pembawa sinyal informasinya pada dasarnya terdiri dari antena pemancar dan antena penerima. Sebelum dirambatkan sebagai gelombang radio, sinyal informasi dalam berbagai bentuknya (suara pada sistem radio, suara dan data pada sistem seluler, atau suara dan gambar pada sistem TV) terlebih dahulu dimodulasi. Modulasi di sini secara sederhana dinyatakan sebagai penggabungan antara getaran listrik informasi (misalnya suara pada sistem radio) dengan gelombang pembawa frekuensi radio tersebut. Penggabungan ini menghasilkan gelombang radio termodulasi. Gelombang inilah yang dirambatkan melalui ruang dari pemancar menuju penerima.
Oleh karena itu, kita mengenal adanya istilah AM dan FM. Amplitudo modulation (AM) atau modulasi amplitudo menggabungkan getaran listrik dan getaran pembawa berupa perubahan amplitudonya. Adapun frequency modulation (FM) atau modulasi frekuensi menggabungkan getaran listrik dan getaran pembawa dalam bentuk perubahan frekuensinya.
Gelombang Mikro
oven microwave
Rentang frekuensi gelombang mikro membentang dari 3 GHz hingga 300 GHz. Frekuensi sebesar ini dihasilkan dari rangkaian osilator pada alat-alat elektronik. Gelombang mikro dapat diserap oleh suatu benda dan menimbulkan efek pemanasan pada benda tersebut. Sebuah sistem pemanas berbasis microwave dapat memanfaatkan gejala ini untuk memasak benda. Sistem semacam ini digunakan dalam oven microwave yang dapat mematangkan makanan di dalamnya secara merata dan dalam waktu singkat (cepat).
Dalam suatu sistem radar, gelombang mikro dipancarkan terus menerus ke segala arah oleh pemancar. Jika ada objek yang terkena gelombang ini, sinyal akan dipantulkan oleh objek dan diterima kembali oleh penerima. Sinyal pantulan ini akan memberikan informasi bahwa ada objek yang dekat yang akan ditampilkan oleh layar radar.
antena radar
Sistem radar banyak dimanfaatkan oleh pesawat terbang dan kapal selam. Dengan adanya radar, pesawat terbang dan kapal selam mampu mendeteksi keberadaan objek lain yang dekat dengan mereka. Di saat cuaca buruk di mana terjadi badai dan gangguan cuaca yang dapat mengganggu pengelihatan, keberadaan radar dapat membantu navigasi pesawat terbang untuk mengetahui arah dan posisi mereka dari tempat tujuan pendaratan.
Sinar Inframerah
Bagaimana remote TV dapat digunakan untuk mematikan atau menyalakan TV? Di sini remote menggunakan pemancar dan penerima sinar inframerah. Tahukah kamu bahwa ada ponsel yang dilengkapi dengan inframerah untuk transfer data dari atau menuju ponsel?
Sinar inframerah (infrared/IR) termasuk dalam gelombang elektromagnetik dan berada dalam rentang frekuensi 300 GHz sampai 40.000 GHz (10 pangkat 13). Sinar inframerah dihasilkan oleh proses di dalam molekul dan benda panas. Telah lama diketahui bahwa benda panas akibat aktivitas (getaran) atomik dan molekuler di dalamnya dianggap memancarkan gelombang panas dalam bentuk sinar inframerah. Oleh karena itu, sinar inframerah sering disebut radiasi panas.
Foto inframerah yang bekerja berdasarkan pancaran panas suatu objek dapat digunakan untuk membuat lukisan panas dari suatu daerah atau objek. Hasil lukisan panas dapat menggambarkan daerah mana yang panas dan tidak. Suatu lukisan panas dari satu gedung dapat digunakan untuk mengetahui daerah mana dari gedung itu yang menghasilkan panas berlebihan sehingga dapat dilakukan perbaikan-perbaikan yang diperlukan.
Dalam bidang kesehatan, pancaran panas berupa pancaran sinar inframerah dari organ-organ tubuh dapat dijadikan sebagai informasi kondisi kesehatan organ tersebut. Ini sangat bermanfaat bagi dokter dalam diagnosis dan keputusan tindakan yang sesuai buat pasien. Selain itu, pancaran panas dalam intensitas tertentu dipercaya dapat digunakan untuk proses penyembuhan penyakit seperti cacar dan encok.
hasil citra foto inframerah terhadap tubuh manusia untuk pemeriksaan kesehatan
Cahaya atau sinar tampak
Dalam rentang spektrum gelombang elektromagnetik, cahaya atau sinar tampak hanya menempati pita sempit di atas sinar inframerah. Spektrum frekuensi sinar tampak berisi frekuensi dimana mata manusia peka terhadapnya. Frekuensi sinar tampak membentang antara 40.000 dan 80.000 GHz (10 pangkat 13) atau bersesuaian dengan panjang gelombang antara 380 dan 780 nm (10 pangkat -9). Cahaya yang kita rasakan sehari-hari berada dalam rentang frekuensi ini. cahaya juga dihasilkan melalui proses dalam skala atom dan molekul berupa pengaturan internal dalam konfigurasi elektron.
Pembahasan tentang cahaya begitu luas dan membentuk satu disiplin ilmu fisika tersendiri, yaitu optik.
Sinar Ultraviolet
Rentang frekuensi sinar ultraviolet (ultraungu) membentang dalam kisaran 80.000 GHz sampai puluhan juta GHz (10 pangkat 17).
Sinar ultraungu atau disebut juga sinar ultraviolet datang dari matahari berupa radiasi ultraviolet memiliki energi yang cukup kuat dan dapat mengionisasi atom-atom yang berada di lapisan atmosfer. Dari proses ionisasi atom-atom tersebut dihasilkan ion-ion, yaitu atom yang bermuatan listrik. Lapisan yang terdiri dari ion-ion ini membentuk lapisan khusus dalam atmosfer yang disebut ionosfer. Lapisan ionosfer yang terisi dengan atom-atom bermuatan listrik ini dapat memantulkan gelombang elektromagnetik frekuensi rendah (berada dalam spektrum frekuensi gelombang radio medium) dan dimanfaatkan dalam transmisi radio.
Karena energinya yang cukup kuat dan sifatnya yang dapat mengionisasi bahan, sinar ultraviolet tergolong sebagai radiasi yang berbahaya bagi manusia (terutama jika terpancar dalam intensitas yang besar). Untungnya, atmosfer bumi memiliki lapisan yang dapat menahan dan menyerap radiasi ultraviolet dari matahari sehingga sinar matahari yang sampai ke bumi berada dalam taraf yang tidak berbahaya. Tentu kamu sudah tahu lapisan apakah itu? ya, lapisan ozon.
lapisan ozon di atmosfer menahan sebagian radiasi ultraviolet
gas untuk spray menyebabkan lubang di lapisan ozon
Sinar ultraviolet juga dapat dihasilkan oleh proses internal atom dan molekul. Sinar ultraviolet juga dapat dimanfaatkan dalam proses sterilisasi makanan dimana kuman dan bakteri berbahaya di dalam makanan dapat dimatikan.
Sinar-X
Sinar-X dikenal luas dalam dunia kedokteran sebagai sinar Rontgen. Dipakai untuk memeriksa organ bagian dalam tubuh. Tulang yang retak di bagian dalam tubuh dapat terlihat menggunakan sinar-X ini.
Sinar-X berada pada rentang frekuensi 300 juta GHz (10 pangkat 17) dan 50 miliar GHz (10 pangkat 19). Penemuan sinar-X dianggap sebagai salah satu penemuan penting dalam fisika. Sinar-X ditemukan oleh ahli fisika Jerman bernama Wilhelm Rontgen saat sedang mempelajari sinar katoda. Cara paling umum untuk memproduksi sinar-X adalah melalui mekanisme yang disebut bremstrahlung atau radiasi perlambatan. Mekanisme ini yang ditempuh oleh Rontgen saat pertama kali menghasilkan sinar-X. Dalam teori radiasi gelombang elektromagnetik diketahui bahwa muatan listrik yang dipercepat (atau diperlambat) akan menghasilkan gelombang elektromagnetik. Selain melalui radiasi perlambatan, sinar-X juga dihasilkan dari proses transisi internal elektron di dalam atom atau molekul.
foto hasil penyinaran sinar-X
produksi sinar gamma oleh inti atom
