How does a Microwave Oven Work?

            Microwave oven takes less than one-tenth of the time taken by other methods of cooking. It has made life much easier for many people. The application of modern technology in domestic appliances has made our lives more comfortable. Washing machines, vacuum cleaners, microwaves ovens, telephones, computers, etc. area few examples that meet the demands of a modern society. How does a microwave oven work?

Microwave Ovens are used for Rapid Cooking at the Appropriate Temperature

            A microwave oven does not have burning flames or red-hot plates like a gas and electric cooker. Its operational mechanism is simple. The food is put into the microwave oven and a switch is pressed. Inside the oven, invisible energy rays bombard the food, and it gets cooked.

Microwave Oven Waves 

            The oven gets its name from the rays that cook the food-the rays are called microwaves. Microwaves are a part of the spectrum of electromagnetic waves, which includes light waves and x-rays. They have wavelengths from about 30 centimeters to a millimeter, which places them between the shortest radio wave and infrared wave. One of the major properties is that it excites the molecules, especially in liquids, which makes them vibrate and get heated up. It is for this reason that food with large water content gets cooked very quickly.

            The source of microwaves in the oven is a magnetron. It is a two electrode valve for generating high frequency oscillations. Microwaves generated by the magnetron travel down a metal duct and are scattered around by a metal fan for even cooking. The molecules strike against each other and the friction produces heat. Water content in the food gets heated up rapidly and the food gets cooked.

            Microwave ovens are potentially a dangerous source of radiation. It is for this reason that microwave ovens are lined with metal and have strong doors. The oven does not function unless the door is closed properly, thus ensuring safety. Most modern ovens contain small computers that automatically cook the food. Microwave ovens are most preferred and widely used in restaurants, hotels and homes.

What are the Wonders of X-Rays?

            X-rays are invisible electromagnetic radiations. Their wavelengths are smaller than those of the visible light. They are high-energy rays, have high penetrating power and travel at the speed of light. They can also pass through the flesh of human beings and animals.

X-Ray Tube Diagram

            A German scientist, Professor Wilhelm Conrad Roentgen in 1895, discovered x-rays. They are sometimes referred to as ‘roentgen x-rays. They were called x-rays x means unknown because not much was known about them earlier. Professor Roentgen was awarded the first Nobel Prize for physics in 1901 for the discovery of x-rays.

Broken Leg Bone Shown on X-Ray Film

            The apparatus used for producing x-rays is called x-ray tube. This tube is made up of hard glass and is fitted with two electrodes, which are connected to high voltage power supply. The electrode connected to the negative terminal is called cathode and the one connected to the positive terminal is called anode. Low pressure is created inside the tube by pumping out air from it. When high voltage is applied to the electrodes, electrons emerge form the cathode and strike the anode or the target which produces x-rays.

            X-rays are very useful to us. They can pass through substances like wood, paper, skin and flesh but are absorbed by bones, iron, lead etc. doctors make use of x-rays to detect the dislocations and fractures of bones, examine the diseases of various organs and presence of stones in kidney and gall bladder. The part of the body to be x-rayed is placed between the x-ray machine and the x-ray film. When the machine is switched on, the rays produce an image on the film, which is then developed like a negative. From the x-ray film, the areas affected by the disease or with defects are located easily.

            X-rays are also used to treat cancer. Airports use x-rays on the baggage of the travelers because with the help of these rays, gold and other valuable germs as well as firearms hidden in the clothes can be detected easily. They are also used to detect cracks and bubbles in metals used for constructing bridges and building purposes.

            X-rays have a damaging effect on body’s cells, and it is for this reason that a person should not be exposed to x-rays quite often and for long durations. Today, using soft x-rays instruments like CAT (computerized auxiliary tomography) scanners are used to detect body abnormalities.