BellworkBellwork

What is a transformer?What is a transformer? A device for increasing or A device for increasing or

decreasing voltage through decreasing voltage through electromagnetic inductionelectromagnetic induction

The Electromagnetic The Electromagnetic SpectrumSpectrum

4/11/144/11/14

AC Generator

Alternating Current and Alternating Current and GeneratorsGenerators

The rotation of the wire cycles The rotation of the wire cycles through a changing magnetic through a changing magnetic fieldfield

AC is easier to transform voltage AC is easier to transform voltage and current and current

Can be transmitted over long Can be transmitted over long distancesdistances

Magnetic Field

Magnetic field strength is dependent on the inverse square law

Inverse Square Law:

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/isq.html#isq

Inverse Square Law: (recap)

Gravitational Force Electric Field Electric Force EM Waves (Radiation) Light Sound Magnetic Field Strength (NEW)

Electromagnetic Wave and Spectrum

Electromagnetic Waves: a wave that consists of oscillating electric and magnetic fields

Electromagnetic Spectrum: electromagnetic waves that range in wavelength and frequency

Electromagnetism Abb.

EM or E&M = Anything Electromagnetic

E&M WavesE&M Waves

Travel at the speed of lightTravel at the speed of light Are transverse wavesAre transverse waves Are produced by accelerating Are produced by accelerating

chargescharges Can propagate without a mediumCan propagate without a medium Transfer energyTransfer energy Have perpendicular electric and Have perpendicular electric and

magnetic fields to propagationmagnetic fields to propagation

Electromagnetic WavesElectromagnetic Waves

Electromagnetic WavesElectromagnetic Waves

Electromagnetic SpectrumElectromagnetic Spectrum

The Electromagnetic Spectrum

Radio Waves Microwaves Infrared Visible Light Ultraviolet X-Rays Gamma Rays

Long wavelengths / Low frequencies

Short wavelengths / High frequencies

The Electromagnetic Spectrum

Radio Waves - communications, TV, communications, TV, radio stationsradio stations

Microwaves – Radar, cell phones, heating food

The Electromagnetic Spectrum

Infrared - heat, heat, photography, night vision photography, night vision gogglesgoggles

Visible Light – Human eye sight

Ultraviolet – Sunburn, purifying water

The Electromagnetic Spectrum

X-Rays - medicine, medicine, astronomy, security astronomy, security screeningscreening

Gamma Rays - cancer cancer treatment, astronomytreatment, astronomy