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 x J/s – energy of waves & frequency are related E=mc 2 – 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