Electromagnetic Waves 12213 Electromagnetic Waves Made by vibrating

Electromagnetic Waves 12/2/13

Electromagnetic Waves • Made by vibrating electric charges • Can travel through space where there is no matter • Energy is transferred between vibrating electric and magnetic fields (instead of particles of matter) • Transverse

Electric and Magnetic Fields • Magnetic Fields: exist around magnets even if there is no matter • Can exert a force on object (ex. Magnet pulling a paper clip) • Electric Fields: exist around electric charges even if there is no matter • Can exert a force on an object (ex. Electricity flowing through a wire)

Electromagnetic Wave:

Properties • Emitted by all objects ▫ They all have charged particles • Vibrating fields exert forces on charged materials • Radiant Energy: amount of energy carried by an EM Wave ▫ Brightness or heat ▫ Depends on amplitude

Cont… • All types travel at 300, 000 m/s in a vacuum ▫“speed of light”=speed limit ▫Why we see lightning before hearing thunder • Travel slowest in solids, fastest in gases c= λf Speed of light = wavelength x frequency 300, 000 m/s = wavelength x frequency

EM Spectrum • Entire range of EM wave frequencies • Humans can only detect small portion with their eyes. Other portions detected with instruments.

Spectrum At a Glance Lowest frequency Longest Wavelength Highest frequency Shortest Wavelength

Uses and the EM Spectrum Region Radio waves Microwaves Infrared Waves Visible Light Ultraviolet waves X-rays Gamma Rays Uses

Uses and the EM Spectrum Region Uses Radio waves Radar, MRI Microwaves Cooking, cell phones Infrared Waves Remote control, night vision Visible Light Seeing color Ultraviolet waves Kill bacteria (sterilize), Vitamin D X-rays Medical images, airports Gamma Rays Treat diseased cells, sterilize

Your Job! • Complete the EM Spectrum WS for tomorrow!