Electromagnetic Radiation PDF

Electromagnetic Radiation Dr Judy Jays 1 Electro Magnetic Radiation 2 Intended learning outcomes By the end of this Lecture, students will be able to Describe the salient features of Electro Magnetic Spectrum Outline the parameters for...

Electromagnetic Radiation Dr Judy Jays 1 Electro Magnetic Radiation 2 Intended learning outcomes By the end of this Lecture, students will be able to Describe the salient features of Electro Magnetic Spectrum Outline the parameters for identification and distinction of different Electromagnetic radiations Correlate different components of Electro Magnetic spectrum with different Spectroscopic methods 3 Electromagnetic radiation (EMR) Electromagnetic (EM) radiation is a form of energy that is all around us and takes many forms such as radio waves, microwaves, X-rays and gamma rays Electromagnetic radiation is energy that is propagated through free space or through a material medium in the form of electromagnetic waves The term also refers to the emission and transmission of such radiant energy 4 Electromagnetic radiation (EMR) They do not need matter to transfer energy EMR consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light The oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation, forming a transverse wave Composed of vibrating electric charges and can travel through space by transferring energy between vibrating electric and magnetic fields A changing magnetic field creates a changing electric field A changing electric field creates a changing magnetic field When an electric charge vibrates, the electric field around it changes creating a changing magnetic field- thus forming an EM wave-The magnetic and electric fields create each other again and again 5 Electromagnetic radiation (EMR) EMR spans an enormous range of frequencies or wavelengths, as is shown by the electromagnetic spectrum. They include: Radio Waves TV waves Radar waves Heat (infrared radiation) Light Ultraviolet Light (This is what causes Sunburns) X-rays Short waves Microwaves, like in a microwave oven Gamma Rays 6 Electromagnetic radiation (EMR) An electromagnetic wave is a transverse wave in that the electric field and the magnetic field at any point and time in the wave are perpendicular to each other as well as to the direction of propagation In free space (i.e., a space that is absolutely devoid of matter and that experiences no intrusion from other fields or forces), electromagnetic waves always propagate with the same speed-that of light EM waves usually travel slowest in solids and fastest in gases They all travel in waves, and also are made of tiny particles 7 Electromagnetic radiation (EMR) An EM wave travels in all directions. Figure only shows a wave traveling in one direction 8 Properties of EM waves All matter contains charged particles that are always moving; therefore, all objects emit EM waves. The wavelengths become shorter as the temperature of the material increases. EM waves carry radiant energy. Speed (km/s) of the EMR depends on the material Vacuum 300,000 Air