Microwave: Electromagnetic Spectrum

Our ancestors would sit around smoky wood fires for hours boiling food, but now all we have to do is press a few buttons and toss food inside a microwave oven and our meal is ready in a minute or two. Microwaves heat the food in a microwave oven. They are quick and efficient because they channel the heat directly to the molecules inside food. In this article, let us learn about microwaves and its various properties and applications.

What are Microwaves?

Microwaves are defined as electromagnetic radiations with a frequency ranging between 300 MHz to 300 GHz while the wavelength ranges from 1 mm to around 30 cm. The microwave radiation is commonly referred as microwaves. They fall between the infrared radiation and radio waves in the electromagnetic spectrum. A few of the properties of microwaves are as follows:

  • Metal surfaces reflect microwaves. Microwaves with a certain wavelength pass through the earth’s atmosphere and can be useful in transmitting information to and from satellites in orbit. Hence, the satellite dishes are made of metal as they reflect microwaves well.
  • Microwaves of certain frequencies are absorbed by water. This property of microwaves is useful n cooking. Water in the food absorbs microwave, which causes the water to heat up, therefore cooking the food.
  • A microwave transmission is affected by wave effects such as refraction, reflection, interference and diffraction.
  • Microwaves can pass through glass and plastic. This is the reason why we use a plastic or glass container in a microwave oven and not metal containers as metal reflects microwaves.

Applications of microwaves

The uses of the microwave are similar to that of radio waves. They are used in communications, radio astronomy, remote sensing, radar and of course, owing to their heating application, they are used in cooking as well. Why do mobile phones use microwaves? Because microwaves can even be generated with the help of small antennas, so the mobile phones need not be of large size.

Microwave - Electromagnetic Spectrum

Observe the frequency and wavelength range of Microwave

Interesting Fact About Microwaves

Something which is not very well known is the use of microwave in getting the first clues to the occurrence of the Big Bang. In the 1960’s, two scientists, who happened to be working with special low noise antennae, noticed something very strange. They were picking up noise from all directions and they noticed something even stranger. The noise from all directions did not vary in its intensity. Arno Penzias and Robert Wilson, the two scientists, figured that if it were coming from anywhere on earth, then the direction would be quite specific… but it wasn’t! They realized that they had discovered cosmic microwave background radiation by mistake! This microwave radiation fills the entire radiation and was our first clue to the occurrence of the Big Bang!

There is a wide belief that since microwaves emit radiations, they are not good for health. But microwaves fall under the low frequencies of the electromagnetic spectrum. They also have low energies. Therefore they do not have enough energy to chemically change substances through ionization. Radiation here means having energy and not radioactivity. And there are some studies which suggest carcinogenic effects (these are not the same as previously mentioned high energy emitting exposure).

Stay tuned with Byju’s to learn more about the electromagnetic spectrum, gamma rays and much more.


Practise This Question

A charge is fixed at one end of an insulating rod of length ‘L’ which rotates with uniform speed about an axis perpendicular to its length and passing through its other end as shown in the figure. This region of space contains a uniform electrostatic field E directed along positive X-axis. The work done by the field when the particle completes two full rotations is?