Radio waves are produced by the accelerated motion of charges in conducting wires.

They are generally in the frequency range from 500 kHz to about 1000 MHz.

The AM (amplitude modulated) band is from 530 kHz to 1710 kHz.

Higher frequencies upto 54 MHz are used for short wave bands.

TV waves range from 54 MHz to 890 MHz. The FM (frequency modulated) radio band extends from 88 MHz to 108 MHz.

Cellular phones use radio waves to transmit voice communication in the ultrahigh frequency (UHF) band.

Microwaves (short-wavelength radio waves), with frequencies in the gigahertz (GHz) range, are produced by special vacuum tubes (called klystrons, magnetrons and Gunn diodes).

Due to their short wavelengths, they are suitable for the radar systems used in aircraft navigation.

Radar also provides the basis for the speed guns used to time fast balls, tennis-serves, and automobiles.

Microwave ovens are an interesting domestic application of these waves. In such ovens, the frequency of the microwaves is selected to match the resonant frequency of water molecules so that energy from the waves is transferred efficiently to the kinetic energy of the molecules. This raises the temperature of any food containing water.

Infrared waves are produced by hot bodies and molecules.

This band lies adjacent to the low-frequency or long-wave length end of the visible spectrum.

Infrared waves are sometimes referred to as heat waves. This is because water molecules present in most materials readily absorb infrared waves (many other molecules, for example, `CO_2`, `NH_3`, also absorb infrared waves). After absorption, their thermal motion increases, that is, they heat up and heat their surroundings.

Infrared lamps are used in physical therapy. Infrared radiation also plays an important role in maintaining the earth-s warmth or average temperature through the greenhouse effect.

Electronic devices (for example semiconductor light emitting diodes) also emit infrared and are widely used in the remote switches of household electronic systems such as TV sets, video recorders and hi-fi systems.

It is the most familiar form of electromagnetic waves. It is the part of the spectrum that is detected by the human eye.

It runs from about `4 - 10^(14)` Hz to about `7 - 10^(14)` Hz or a wavelength range of about 700 - 400 nm.

Our eyes are sensitive to this range of wavelengths.

Different animals are sensitive to different range of wavelengths. For example, snakes can detect infrared waves, and the -visible- range of many insects extends well into the ultraviolet.

It covers wavelengths ranging from about `4 - 10^(-7)` m (400 nm) down to `6 - 10^(-10)`m (0.6 nm).

Ultraviolet (UV) radiation is produced by special lamps and very hot bodies.

The sun is an important source of ultraviolet light.

But fortunately, most of it is absorbed in the ozone layer in the atmosphere at an altitude of about 40 - 50 km.

UV light in large quantities has harmful effects on humans. Exposure to UV radiation induces the production of more melanin, causing tanning of the skin.

UV radiation is absorbed by ordinary glass. Hence, one cannot get tanned or sunburn through glass windows.

Welders wear special glass goggles or face masks with glass windows to protect their eyes from large amount of UV produced by welding arcs.

Due to its shorter wavelengths, UV radiations can be focused into very narrow beams for high precision applications such as LASIK (Laser assisted in situ keratomileusis) eye surgery. UV lamps are used to kill germs in water purifiers.

Beyond the UV region of the electromagnetic spectrum lies the X-ray region.

It covers wavelengths from about `10^(-8)` m (10 nm) down to `10^(-13)` m (10-4 nm).

One common way to generate X-rays is to bombard a metal target by high energy electrons.

They lie in the upper frequency range of the electromagnetic spectrum and have wavelengths of from about `10^(-10)`m to less than `10^(-14)`m.

This high frequency radiation is produced in nuclear reactions and also emitted by radioactive nuclei.

They are used in medicine to destroy cancer cells.

Table summarizes different types of electromagnetic waves, their production and detections.