The Electromagnetic Spectrum

Oooh…aaah

What is it?

• A spectrum is a RANGE of things• The Electromagnetic Spectrum

(EM Spectrum) is a RANGE of electromagnetic waves arranged by wavelength

What are EM Waves again?

• EM waves • are waves that do NOT need a medium to travel through• Contain intersecting electric & magnetic fields• Are often called “radiation” because of the high energy they

possess• All move at the “speed of light”• Include:

– Radio waves – Infrared radiation– Visible light– Ultraviolet radiation– X-rays– Gamma Rays

Radio Waves?

• Radio waves (lowest energy)– have the longest wavelengths and the shortest frequency.– Include

• AM radio (Amplitude Modulation)– very low energy

• TV channels– “high” energy

• Shortwave Radio• FM radio (Frequency Modulation)

– medium energy

• Radar• Microwave radiation

Infrared?

• Infrared rays – Heat Radiation

Ultraviolet?

• Ultraviolet– Energy from the sun (and stars)– Causes sunburn AND skin cancer– Kills bacteria– Fluoresces in the presence of bodily fluids

X-Rays?

• X-rays– Short wavelength, very high frequency– Can pass thru solid objects– Used in medicine to form images of bone and

internal organs

Gamma Rays?

• Gamma Rays– Shorter wavelength– Higher frequency– More energy– Given off during nuclear reactions– Changed David Bruce Banner into the Incredible

Hulk!!!

What’s all this photon stuff?

• Photons are PARTICLES of light or other EM waves– Albert Einstein and Max Planck studied them which

led to• h=6.626 x10-34 J/s

– energy of waves & frequency are related• E=mc2

– Energy & mass & speed of light particles are related• ALL em waves move at the speed of light– 299,792,458 m/s– 186,000 miles/sec