If you think of a kitchen appliance that has revolutionized modern home kitchens, it must be the microwave oven. It is built and mostly used for heating foods quickly.
It is most useful for otherwise time-consuming activities such as melting butter or heating water. It is now most common in homes and the office, although it was initially used in commercial kitchens.
Read this article to find out how microwave ovens work.
How was microwave oven invented?
During the second world war while walking past a microwave radar, American engineer Percy Spencer noticed that the chocolate bar had melted in his pocket.
Spencer discovered that not only could the powerful microwave energy emerging from magnetrons be used to chase enemies in battle, but also can cook pasta once in a while.
This discovery, was found to be irresistibly delightful, it was innovative but merely accidental. Spencer’s first food item then intentionally fried with microwaves was popcorn.
An egg was what he tried next without putting it over fire, from a distance, as if something magical has happened. The moment was historic without any doubt.
Our ancestors would’ve undoubtedly loved the microwave ovens! They could have just thrown everything in the microwave oven, pushed a few buttons, and had a meal ready in a minute or two instead of resting around smoky wood flames for hours on end, getting the buffalo stew ready for their stone-age mates.
The impact of microwave ovens in households
The invention raised household comfort to a new level when microwave ovens became popular in the 1970s. A conventional oven heats food from the outside very slowly, but to cook food more uniformly, a microwave oven uses small, high-powered electromagnetic waves.
For this reason, it is possible for a microwave oven to cook food such as a meat joint approximately six times faster than a traditional range.
Microwave ovens often save electricity, since without waiting for the oven to heat up to a high temperature first, you can cook instantly. Let’s take a closer look at the way it works!
There’s an enormous application of science and engineering behind microwaves, but it can all be broken down into simple bits to grasp and digest.
How does it work?
Microwave oven primarily operates by producing radiation in the form of microwave which is passed through the food.
Microwaves are not unique to microwave ovens but are electromagnetic waves with a frequency that ranges between 300 MHz and 300 GHz (approximately 1 m and 1 mm wavelengths). Usually, microwave ovens use a frequency of 2450 MHz (a 12.24 cm wavelength).
Whats inside the oven?
There is a microwave generator inside the strong metal case, called a magnetron. The magnetron takes energy from the power outlet when you start to cook food and transforms it into high-powered, 12 cm (4.7 inches) radio waves.
Using a channel called a waveguide, the magnetron blast the waves into the food compartment. The food is on a turntable, slowly rotating around so that the microwaves cook it evenly.
Inside the microwave oven, a part called the magnetron produces microwaves from electricity. A transformer transforms standard household electricity from a wall socket of 120 volts to approximately 4,000 volts or higher to power the magnetron.
In the middle of the magnetron, the voltage heats a filament, boiling off electrons.
As the filament heats up, electrons are released. The electrons will rush out toward an anode or positive terminal surrounding the filament in a straight line.
Still, two ring magnets bend the electrons back toward the filament above and below the anode and travel around in a circular path.
At a frequency of 2450 MHz, domestic microwave oven runs with a power normally ranging from 500 to 1100 watts. An electronic tube called a magnetron generates microwave.
The microwaves are spread in the oven cavity once the oven is turned on and mirrored by a stirrer fan to distribute the microwaves in all directions. The metal sides of the oven cavity reflect them, and the food absorbs them.
How is the heat used efficiently?
Heating uniformity in the food is usually helped by placing the food in the oven on a revolving turntable. When they consume microwave energy, water molecules in the food vibrate, and the friction between the water molecules results in heating that cooks the food.
Unlike regular ovens, only in the food and not in the surrounding oven cavity are microwaves absorbed. It is best to use the dishes and containers solely designed for cooking in microwave ovens.
When overheated, some materials, such as plastics that are not suitable for microwave ovens can melt or burst into flames.
Microwaves do not explicitly heat food containers intended for cooking in the microwave. Typically, these materials just get warm from being in touch with the hot food.
Microwave radiation is the energy field that is emitted by microwave ovens and other devices. Microwave radiation consists of long, narrow radio waves that have high frequency ranges and are generally beyond the human sensory range.
Like other electromagnetic waves except light, microwaves are invisible to the human eye. While microwaves are unnoticeable to the human eye, they are harmful to the health of humans when exposed for prolonged periods of time.
How much is radiated by the ones at home?
The amount of microwave radiation emitted by microwave ovens varies depending on their wattage. Microwave is also a type of electromagnetic radiation with different frequencies ranging from one gigahertz to one thousand gigahertz corresponding to various ranges.
The above broad definition encompasses both UHF and EHF channels; however, UHF waves are generally associated with lower frequencies and are thus of less severe effects on our health than EHF waves.
These shortwaves are thought to produce less acute physical injuries when people are exposed to them.
Although microwave ovens emit microwaves in all directions, they have the strongest impact when the microwaves are deflected back to the device.
The deflection is produced due to the focusing effect of the microwave ovens on air molecules which are in motion.
The effects of the microwave radiation may vary according to the frequencies of the waves.
Some microwaves generate heat which may cause burns; other microwave ovens generate sound waves that may produce inner ear discomfort; and some microwave ovens produce gamma rays that are harmful if exposed.
Is microwave radiation from ovens harmful?
Although microwave ovens are mostly safe, their continued use may bring about some negative health issues like headaches, nausea, and stress. Long term exposure to microwaves can also cause skin cancer.
Since the microwave ovens emit heat in all directions, it may generate undesirable effects like uneven heating of one area by damaging a nearby part.
When this happens, it can cause burns or injury to people or even damage to property. In addition, microwave radiation is extremely harmful to people who are under the influence of drugs and alcohol.
To ensure that you are not harmed by microwave radiation, you must ensure that you are not exposed to the device in the areas where the device is being used.
For this purpose, you must ensure that the oven is kept in its original spot or at least have a cover to protect it.
Few things to follow in domestic usage of microwave ovens
Oven manufacturers urges the users not to use an empty oven. The microwave energy can be reflected in the magnetron when theres no food in it and can destroy it.
Users of microwave ovens should carefully read and comply with the manufacturer’s instructions, as new ranges differ significantly in design and efficiency.
Most modern ovens are designed to withstand food that has been packaged with metal, manufacturers do not recommend to put material made of metal in the oven, particularly not near the walls of the interior.
Because this causes electrical arcing and damage to the oven walls.
Also, food wrapped in aluminium foil will not be cooked because it reflects microwaves, while food not covered in the metal wrap can receive more energy than expected, causing uneven cooking.
Precautions that needs to be followed
Radiation from the microwave will heat up the body tissues the same way it heats up foodstuffs. A painful burn may be caused by exposure to high levels of microwaves.
The eyes, and the testicles, are especially susceptible to radio frequency heating because they have little blood flow to remove excess heat.
The eye lens is especially susceptible to extreme heat, and cataracts can be caused by exposure to high microwave levels. But these will be only caused through exposure to massive quantities of microwave radiation.
In other words, you might expect more of the energy coming in from the power cable to be transformed into heat in your food and less to be lost in other ways. You would expect a microwave to be much more potent than other forms of cooking.
In general, that’s right: cooking in a microwave is cheaper and more comfortable than cooking in a conventional oven because before you can cook, you don’t have to heat the stove itself.
But that’s not the story as a whole. A microwave oven isn’t the safest thing to use if you want to heat just a small amount of food (or a cup of hot water).
You’re also powering an electric motor that spins a relatively heavy glass turntable when you microwave anything, in addition to putting energy into the food.
Although you don’t have to heat the food compartment for the oven to cook after it’s been on for a while, a microwave oven gets pretty hot, so there are some heat losses.
Cook food – Regular oven Vs Microwave oven
Differentiating conventional ovens with microwave is easier. To transform electricity into microwaves, a magnetron is not always hundred percent efficient: it will get hot itself.
And an electronic circuit, a timer monitor, and perhaps a cooling fan have to be driven as well. All these things, taken together, makes a microwave less energy efficient than it should be.
If it is from a microwave or a regular oven, some nutrients break down when exposed to heat. Maybe the most evident example is vitamin C.
But cooking with a microwave, since microwave cooking times are shorter, does a better job maintaining vitamin C and other nutrients that break down when heated.
Cooking vegetables in water eliminates some nutritional value since the nutrients leach out into the cooking water. Boiled broccoli, for example, loses glucosinolate.
This compound contains sulfur that can give the vegetable its cancer-fighting properties (as well as the taste that many find distinctive and some find disgusting).
Is steaming vegetable any better in a microwave oven ? In some instances, indeed. For example, more glucosinolate holds on to steamed broccoli than boiled or fried broccoli.
Maintenance Processes of Microwave ovens
It would be best if you did not run an empty microwave, as it will overheat the microwave and destroy it. There’s certainly no harm a minute or two can do, but don’t gamble it any longer than that.
There is a timer in individual microwaves that can be used independently of the microwave feature, which is okay.
Luckily, microwave ovens are almost trouble-free. The owner can fix many of the issues themselves.
For instance, if the power cord gets broken, it will be essential to repair the interlocking switches, fan, thermal cutout, turntable motor, temperature sensor, light bulb, or the door may not close properly.
Never try a microwave oven to operate the magnetron. It is incredibly dangerous. Make sure the power is on at the outlet and test the electrical cord if the microwave is not going to operate at all.
Check the fuse and, if it is defective, repair it.
To ensure that it closes properly, check the door as well. Test the fan and, if necessary, replace it. Always check the door interlock switch, the thermal cutout, and the fan.
Inspect the plastic coupling underneath the tray if the carousel doesn’t move. Check the assembly of the roller to make sure the tray sits at the level of the turning mechanism.
Take it to a service center that operates on microwave ovens if you ever have issues with it such as an exploded fuse, an utterly awful mess of decayed burnt-on food, or a thriving cockroach culture inside.
It should be sealed appropriately as long as there is no severe damage to the door (a 6-inch hole will count as severe damage), and the door fits square.
There should be no leakage from there, as long as the waveguide is securely installed and undamaged.
Ensure the metal cover has all its fingers placed across the front (although there should be limited microwave leakage into the electronics bay with an adequately equipped magnetron).