L 29 Electricity and Magnetism  Review- magnetism- what is a magnet?

 Sana 03.02.2018 Hajmi 472 b. #25899 • Faraday’s Law of Electromagnetic Induction

• induced currents
• electric generator
• eddy currents

Laws of Magnetism  The electric motor • the phenomenon that a changing magnetic field can produce a current is called electromagnetic induction Induced currents (a) • The induced current only appears when the magnet is being moved • If the current in the primary windings were DC, there would be NO induced current in the secondary circuit. electric generators The transformer • an induction stove uses eddy currents to cook food  • Laws of magnetism.—

• currents produce magnetic fields
• magnetic field lines are closed loops
• Faraday’s law of electromagnetic induction.— a changing magnetic field can produce a current (induced currents) • Maxwell added the last piece of the puzzle • EM waves include radio, microwaves, x-rays, light waves, gamma rays . . . . . . • an electromagnetic wave is a combination of electric and magnetic fields that vibrate together in space and time in a synchronous fashion Electric Field Magnetic Field the generation of an electromagnetic wave • the electromagnetic wave is a transverse wave, the electric and magnetic fields oscillate in the direction perpendicular to the direction of propagation • an electromagnetic wave must have both an electric and magnetic field component  Electromagnetic Waves  Common frequency bands Detecting (receiving) the Wave • for example, the wavelength of a 1 MHZ radio wave is: wavelength = speed/frequency = 300,000,000/1,000,000 = 300 meters • AM  the information is coded into the way that the amplitude is modulated Electromagnetic spectrum • all this shaking energizes the molecules making the water hotter and hotter. 