What are 5 uses of microwaves?
Microwaves are suitable for wireless transmission of signals having larger bandwidth. Microwaves are most commonly used in satellite communications, radar signals, phones, and navigational applications. Other applications where microwaves used are medical treatments, drying materials, and in households for the preparation of food.
How are old microwaves better then new microwaves?
- Ensure that you and the children are not always standing against your microwave when you turn it on. ...
- If the door on your microwave oven does not close due to damage or warping, you should not use it.
- When heating water and other liquids in your microwave oven, take no more than the time specified in the manufacturer's instructions.
Is your microwave harmful for health?
Microwaves are a safe, effective, and highly convenient cooking method. There is no evidence that they cause harm — and some evidence that they are even better than other cooking methods at preserving nutrients and preventing the formation of harmful compounds.
What are three ways microwaves are used?
Microwaves are the electromagnetic waves which are produced by the specially designed vacuum tubes such as magnetrons, gunn diodes, etc. They are used in the following manner: 1. In Radar systems for the navigation. 2. in microwave ovens for the cooking purposes. 3. In observing the movements of trains on rails.
How are microwaves produced naturally?
Cosmic microwave background radiation is a natural source of microwaves. The radiation is studied to help scientists understand the Big Bang. Stars, including the Sun, are natural microwave sources. Under the right conditions, atoms and molecules can emit microwaves.
How are microwaves produced science?
Microwaves are a form of electromagnetic radiation, just like light and radio waves. They come from applying a large voltage to a thing called a cavity magnetron, which involves the interactions of electrons with a magnetic field.
How do electrons produce microwaves?
As the electrons nip past the cavities, the cavities resonate and emit microwave radiation. Think of the electrons passing energy to the cavities, making then resonate like someone blowing on the open end of a flute—only producing microwaves instead of sound waves.
How are microwaves produced write its uses?
Solution : Microwaves are produced by special vacuum tubes such as Klystron, magnetrons etc.
Uses of microwaves : (i) They are used in long distance telephone communication system. (ii) They are also used in microwaves ovens for cooking / warming food.
How does microwave work in physics?
The principle behind the microwave is very simple – it's all about the atom. When you add energy to an atom or molecule, it vibrates. More energy equals more vibrations, and this generates heat.
Is microwaved food safe?
Food cooked in a microwave oven is as safe, and has the same nutrient value, as food cooked in a conventional oven.
How are microwaves transmitted?
Microwave transmission is the transmission of information by electromagnetic waves with wavelengths in the microwave range (1 m - 1 mm) of the electromagnetic spectrum.
How do microwaves travel?
Microwaves travel solely by line-of-sight paths; unlike lower frequency radio waves, they do not travel as ground waves which follow the contour of the Earth, or reflect off the ionosphere (skywaves).
What frequency is a microwave?
“Microwave” frequencies are formally defined as those above 300 MHz (wavelengths less than 1 m), but informally we consider microwave frequencies as being above about 1 GHz.
How microwaves are produced state their properties?
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.
How are microwaves produced class 12 physics?
(i) Microwaves are produced by special vacuum tubes like the klystron/ Magnetron / Gunn diode. The frequency of microwaves is selected to match the resonant frequency of water molecules, so that energy is transferred efficiently to the kinetic energy of the molecules.
How are microwaves produced give two important uses?
Solution : Properties (i) Microwaves are e.m. waves of frequency range 1GHz to 300GHz.
(ii) They are produced by special vaccum tube (Klystrons, magnetrons etc).
Uses
(i) Microwaves are used for cooking purposes e.g. microwave ovens
(ii) Microwaves are used in radar systems.
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...
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 g...
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 ma...
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...
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...
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 vi...
Metal Box and Microwave Cavities
The first part of a microwave is the metal surface that contains the inner cavity. The metal used in a microwave reflects microwave radiation and contains it. The metal walls are typically stainless steel, and manufacturers coat them in thin enamel to prevent rusting.
Magnetron
The magnetron tubes produce the microwave energy that cooks your food products.
Waveguide
The waveguide directs the energy from the magnetron into the microwave cavity.
Transformer or Inverter
The transformer takes electrical currents from a power source and adjusts them to the needs of the microwave. Alternatively, some models use an inverter that does not have to step the electric currents up or down to power the microwave oven.
Turntable and Glass Plate
A turntable motor and turntable mechanism sit at the center of the microwave cavity. Most of the time, a glass or ceramic plate sits above the turntable mechanism, and that is where you place your food.
Circuit Board and Control Panel
The circuit board is the computer that controls the microwave and operates several safety switches inside the appliance. In addition, the control panel lets you set programs and cooking timers.
Microwave Door
The microwave door typically contains a metal mesh that stops microwave energy from leaving the cavity but still allows you to monitor your food while it cooks visually.
How does a microwave oven work?
Microwaves play an increasingly wide role in heating and cooking food. They are absorbed by water and fat in foodstuffs (e.g., in the tissue of meats) and produce heat from the inside.
What is the purpose of microwaves?
Microwaves are the principal carriers of high-speed data transmissions between stations on Earth and also between ground-based stations and satellites and space probes. A system of synchronous satellites about 36,000 km above Earth is used for international broadband of all kinds of communications—e.g., television and telephone.
How is infrared radiation absorbed?
Infrared radiation is absorbed and emitted by the rotations and vibrations of chemically bonded atoms or groups of atoms and thus by many kinds of materials. For instance, window glass that is transparent to visible light absorbs infrared radiation by the vibration of its constituent atoms.
What is the wavelength of a microwave?
Microwaves. The microwave region extends from 1,000 to 300,000 MHz (or 30 cm to 1 mm wavelength). Although microwaves were first produced and studied in 1886 by Hertz, their practical application had to await the invention of suitable generators, such as the klystron and magnetron. Microwaves are the principal carriers of high-speed data ...
Why is microwave radar important?
Microwave radar is therefore widely used for guiding airplanes and vessels and for detecting speeding motorists. Microwaves can penetrate clouds of smoke but are scattered by water droplets, so they are used for mapping meteorologic disturbances and in weather forecasting.
How does sunlight convert energy into electricity?
Photovoltaic devices, on the other hand, convert the energy in sunlight directly to electricity by use of the photovoltaic effect in a semiconductor junction.
Why is the infrared spectrum transparent?
Atmospheric haze and certain pollutants that scatter visible light are nearly transparent to parts of the infrared spectrum because the scattering efficiency increases with the fourth power of the frequency. Infrared photography of distant objects from the air takes advantage of this phenomenon.
How to make a microwave oven?
First, the frame is formed using automatic metal-forming presses that make about 12 to 15 parts per minute. The frame is then rinsed in alkaline cleaner to get rid of any dirt or oil and further rinsed with water to get rid of the alkaline solution.
Where do microwaves go in the microwave?
Manufacturers vary the means by which they disburse microwaves to achieve uniform cooking patterns: some use dual stirrer fans located on opposite walls to direct microwaves to the cavity, while others use entry ports at the bottom of the cavity, allowing microwaves to enter from both the top and bottom.
How does a waveguide work?
The waveguide is connected to the magnetron on top of the protruding antenna, while a blower motor used to cool the metal fins of the magnetron is attached directly to the tube. Finally, a plastic fan is attached to the motor, where it will draw air from outside the oven and direct it towards the vanes.
What are the parts of an oven made of?
The hardware that links the various components consists of a variety of metal and plastic parts such as gears, pulleys, belts, nuts, screws, washers, and cables.
What is the most common use of microwave energy?
Microwaves themselves are used in many different applications such as telecommunication products, radar detectors, wood curing and drying, and medical treatment of certain diseases. However, certain of their properties render them ideal for cooking, by far the most common use of microwave energy.
How does a cook switch work?
9 The cook switch provides power to the transformer by energizing a relay and a timer. The relay is mounted close to the power transformer, while the timer is mounted on the control board. The defrost switch works like the cook switch, activating a motor and timer to operate the defrost cycle. Also mounted on the control board are a timer bell that rings when the cooking cycle is complete and a light switch that allows viewing of the cavity. A number of interlocking switches are mounted near the top and bottom of the door area. The interlocking switches are sometimes grouped together with a safety switch that monitors the other switches and provides protection if the door accidently opens during oven operation.
Why are microwaves important?
Because of their speed and convenience, microwave ovens have become an indispensable part of modern kitchens. Many developments in the microwave market and allied industries are taking place fairly rapidly. For example, foods and utensils designed specially for microwave cooking have become a huge business.
What kind of energy does a microwave use?
Microwave ovens cook foods by injecting them with, surprise, microwaves —a form of energy. These electromagnetic waves are invisible to the human eye and fall between radio waves, which are longer in wavelength, and infrared waves, which are shorter.
When did microwaves start heating?
Microwave ovens were life altering from the moment they began humming and heating in homes of the 1970s. The sprinter to the conventional oven’s cross-country runner, microwaves quickened the process of cooking and reheating meals, saving time and increasing the potential for leisure over work.
Why do microwaves heat food?
Because the microwaves can travel only so far into an object before losing momentum, the outsides of thicker foods become heated by microwaves, and the insides are heated subsequently by the conductive transfer of heat from the outsides.
What is a microwave box?
It seems to be a magical metal box that spins and heats food by invisible means rather than heating the air and everything around it by conduction from a flame (as was the norm). Microwave users also came to accept the odd rules of the technology: no metal, no meltable plastics, and stir to cook evenly.
Does metal absorb microwave?
Certain types of plastics are able to absorb microwaves like foods do, making them prone to melting, dissolving, and therefore contaminating the food cooked on or in them. Metal reflects microwaves and therefore interferes with the movement of the waves inside the ovens.
Overview
History
Microwaves were first generated in the 1890s in some of the earliest radio experiments by physicists who thought of them as a form of "invisible light". James Clerk Maxwell in his 1873 theory of electromagnetism, now called Maxwell's equations, had predicted that a coupled electric field and magnetic field could travel through space as an electromagnetic wave, and proposed th…
Propagation
Microwaves travel solely by line-of-sight paths; unlike lower frequency radio waves, they do not travel as ground waves which follow the contour of the Earth, or reflect off the ionosphere (skywaves). Although at the low end of the band they can pass through building walls enough for useful reception, usually rights of way cleared to the first Fresnel zone are required. Therefore, on the surface …
Antennas
The short wavelengths of microwaves allow omnidirectional antennas for portable devices to be made very small, from 1 to 20 centimeters long, so microwave frequencies are widely used for wireless devices such as cell phones, cordless phones, and wireless LANs (Wi-Fi) access for laptops, and Bluetooth earphones. Antennas used include short whip antennas, rubber ducky antennas, sleeve dipo…
Design and analysis
The term microwave also has a more technical meaning in electromagnetics and circuit theory. Apparatus and techniques may be described qualitatively as "microwave" when the wavelengths of signals are roughly the same as the dimensions of the circuit, so that lumped-element circuit theory is inaccurate, and instead distributed circuit elements and transmission-line theory are more useful methods for design and analysis.
Microwave sources
High-power microwave sources use specialized vacuum tubes to generate microwaves. These devices operate on different principles from low-frequency vacuum tubes, using the ballistic motion of electrons in a vacuum under the influence of controlling electric or magnetic fields, and include the magnetron (used in microwave ovens), klystron, traveling-wave tube (TWT), and gyrotron. Th…
Microwave uses
Microwave technology is extensively used for point-to-point telecommunications (i.e. non-broadcast uses). Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower …
Microwave frequency bands
Bands of frequencies in the microwave spectrum are designated by letters. Unfortunately, there are several incompatible band designation systems, and even within a system the frequency ranges corresponding to some of the letters vary somewhat between different application fields. The letter system had its origin in World War 2 in a top secret U.S. classification of bands used in radar sets; this is the origin of the oldest letter system, the IEEE radar bands. One set of microwa…