What is Microwave?
Microwaves attract all the attention when it comes to making our lives simpler in terms of cooking food. This article covers the properties of the microwave and also its production. We will also be discussing the difference between radio waves and microwaves. If you encounter any doubts while reading this article then the frequently asked questions at the end may help you out with those.
Microwaves are electromagnetic radiation as are ultraviolet radiation X rays, gamma rays, and radio waves. Microwaves have a range of applications including radar communications and best known by most people, cooking.
During primitive days, ancestors used wood, coal to cook their food. With the evolution of human beings, the cooking style also changed, and people started using LPG. Today, in modern times, we have significantly evolved with technology and use microwave radiation for cooking food quickly at our convenience.
So, let’s understand microwave radiation. Microwave radiations are electromagnetic radiations with a frequency range of 300 Mhz – 300 GHz. The wavelength of the microwave spectrum range is between 1 mm to 30 cm. These radiations are often called a microwave. In the electromagnetic spectrum, the microwave is present between infrared and radio waves. With this understanding, let us learn the characteristics of microwaves.
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Properties of Microwaves
Microwaves are reflected by metal surfaces.
They pass through glass and plastics.
They can pass through the atmosphere. Thus, microwaves are used phenomenally in information transmission back and forth to the satellite. It is why satellite dishes are composed of metal content as metal reflects the microwave radiation.
Water absorbs a particular frequency of microwaves. This feature of microwaves is utilized in cooking food. Microwaves are absorbed by the water content present in food, which in turn heat the food. By heating, the atoms and molecules of water in food start vibrating. As a result, the temperature of the food increases, and the food is cooked.
Microwave transmission is affected by wave effects like reflection, refraction, diffraction, and interference.
The time for which the material is exposed to the radiation intensity determines the amount of heating.
Microwaves are reflected by the conducting surfaces and travel in a straight line.
They radiate electromagnetic energy with a shorter wavelength.
The most suitable for the radar systems that are used in aircraft navigation due to their shorter wavelength.
How are Microwaves Produced?
Microwaves are generated by vacuum tubes devices. These devices work on the ballistic movement of electrons operated by either magnetic or electric fields. There are a few examples of microwave emitters like cavity magnetron, the klystron, the traveling-wave tube(TWT), and many more. These instruments work based on clumps of electrons flying ballistically through them, instead of using a constant flow of electrons. Lower power microwaves can be produced by some solid-state devices such as the FET (field effect transistor), the tunnel diode, the Gunn diode, and the IMPATT diode.
Production of Microwaves
Microwaves are produced by special vacuum tubes like the klystron, magnetron, and Gunn diode.
The frequency of microwaves is selected to match the resonant frequency of motor wall equals so that the energy is transferred efficiently to the kinetic energy of the molecules.
(a) Associated with the greenhouse effect.
(b) and also in remote switches of electrical appliances.
Radio Waves v/s Microwaves
Fun Facts
Did you ever think that we use a plastic or glass container in a microwave oven and not metal containers to heat or cook food? It is because the metal is microwave reflectors. On the other hand, glass and plastic allow the microwave to pass through them.
It is very commonly believed that a microwave is not suitable for health as it emits radiation. Nevertheless, there is a point to note that microwaves use the electromagnetic spectrum at low frequencies. Hence microwave radiations have low energy. Due to this insufficient energy, microwave radiations are not capable of changing the food substance chemically via ionization.
Microwaves traversed through the atmosphere will be absorbed by water. This process is utilized by the weather department to monitor rain. If weak signals are reaching the detector, microwaves have passed through more rain. It helps in the analysis of rainfall. The weaker the signal reaching the detector, the more rain has passed through the microwave radiation
Conclusion
This is all about microwaves, their properties, production, and uses. Focus on its features and find out the difference between microwaves and other radiation waves. Understand how it is being used in different aspects of our modern lives.
FAQs on Microwaves
1. Do microwaves cook food From the Inside Out?
It has to pass from electric heating elements of gas burners positioned in the bottom and sides of the two currents to the food which is cooked by conduction in a conventional oven. This is the reason a cake is cooked in a conventional oven as it can be burned on the edges and not properly cooked in the middle. It is generally cooking more quickly and evenly as microwaves are exciting molecules right to the food.
2. Are microwave ovens safe?
In a microwave oven, the cooking cavities a sealed metal container by using a microwave normally, and the waves can't leak out. The inside of the glass door has a grid of metal stuck to the back; those holes are so small to let microwaves through. Some distance away and outside the cooking cavity even a leaking microwave can produce only tiny amounts of electromagnetic radiation.
3. Who invented the microwave oven?
One day when Percy Spencer switched on magnetron, he found a chocolate bar in his pocket. The bar quickly melts due to the heat generated by the magnetron that surprised him. This made him think that Magnetron can be used to cook food. After cooking some popcorn he finally realized that he could cook all types of food after the development of a microwave oven.
4. How can exposure to RF radiation be avoided?
Avoid jobs with increased RF exposure. Limit the time that you spent near equipment appliances and other devices that give off RF radiation such as Wi-Fi routers. Restrict the time you spend with a mobile phone placed against your ear or close to another part of your body.
5. Briefly explain the applications of microwave
Microwave is commonly used in the oven for cooking food. At the same time, microwaves play a crucial role in communication technology as explained below.
Microwaves are used in cell phones. Microwave is the carrier of the signals of cell phones. With the help of frequency modulation, the caller's sound waves are encoded in microwaves by changing their frequency. These encoded microwaves are transmitted to cell towers via air. Then wave traverses to the switching center from cell tower, and finally, it reaches another cell tower of the receiver. At the receiver end, again, the microwave is decoded to sound waves. The microwave is interrupted by the building. That's why cell towers are on the outskirts and well above the ground to prevent obstruction.
Microwave is used in Radio Detection and Ranging (RADAR) technology. This technology is utilized in radar guns to find overspeeding vehicles. Radar guns send a small microwave. Microwave is reflected by the metallic surface of the vehicle and thus detected by the receiver of the radar gun. This feature is also utilized in tracking storms, managing air traffic.
6. How is the food heated or cooked inside a microwave oven?
Water molecules strongly absorb the microwave energy of a specific frequency. The absorption of the microwave by water causes water molecules to vibrate, which results in the increment of the kinetic energy of the water molecules. Due to this the temperature of the materials containing water molecules increases. If we use frequency in the microwave, which is completely absorbed, the chances are that the food will only be cooked outside. As most of the energy is absorbed by the outer surface of food, not enough energy penetrates it. Thus, the setting of the microwave oven is such that it emits the microwave of frequency, which also penetrates the food. Once the microwave radiation penetrates the food, heat is spread all over the food by the mechanism of conduction and convection.
We should be cautious while using the microwave oven because our human body contains water molecules in our cells. Microwave oven radiation at high intensity could be dangerous as it can burn the body tissue by heating the cells. The radiation is limited inside the oven by placing the reflecting metal case and metal grid in the door.