• Energy is transmitted as electromagnetic radiation through the space.                                                           • They consist of both electric and magnetic fields which are perpendicular to each other.                             • Velocity of all the electromagnetic radiation in vacuum is; 3.00 x 10⁸ m s-1 which is the velocity of light. • When is the wave length and is the frequency, the velocity of an electromagnetic wave- C = υλ.                 • The energy of an electromagnetic wave E = hυ (E is the energy of a photon.) where h is a constant. It is named as Planck’s constant. Planck constant = 6.624 x 10^-34 J s

Arrangement of the electromagnetic radiations in the ascending order of the frequency produces the electromagnetic spectrum.

Uses of the radiations belonging to different ranges of the electromagnetic spectrum

• Radio waves : Used for communication through television and radio media.

• Radar waves : Used in naval and aeronautical security systems.

• Micro waves : Microwave ovens function due to these waves. Used in cellular phones.

• Infrared waves : Used in physiotherapy treatments. Used in sending signals by remote control devices and also in analytical work using spectroscopic methods.

• Visible waves : Vision and photography are due to waves in this range. Used in colorimetric analysis.

• Ultraviolet waves : Used for sterilization and to read confidential symbols in currency notes etc. Also used in spectroscopic analysis.

• X- rays : Used in X ray photography and in studies of the structure of crystals etc.

• γ rays : Used in the treatment of cancer.