Electromagnetic Waves

Electromagnetic Waves

Electromagnetic Spectrum • The electromagnetic radiation includes a wide range of frequencies and wavelengths. • The electromagnetic spectrum is the entire range of frequencies of electromagnetic radiation

Electromagnetic Spectrum

Low Energy Large Wavelength Low Frequency

High Energy Small Wavelength High Frequency

Electromagnetic Spectrum • You should know the order of electromagnetic radiation from low frequency to high frequency: • Lowest frequency – – – –

Radio waves Microwaves Infrared radiation Visible light (red, orange, yellow, green blue, violet) – Ultraviolet – X-rays – Gamma rays.

• Highest Frequency

Energy and the Electromagnetic Spectrum • The energy of electromagnetic radiation is directly proportional to the frequency. • Electromagnetic radiation with higher frequency than visible light has higher energy. This is why ultraviolet light can burn your skin and X-rays and gamma rays can damage tissues. • Electromagnetic radiation with a lower frequency than visible light has less energy.

Rays that hit the earth!

Wavelength and the Electromagnetic Spectrum • Higher frequency electromagnetic waves have shorter wavelengths • Wavelengths vary greatly from long wavelengths (many meters) to very short wavelengths (the size of atomic nuclei).

Radio Waves Radio Waves • Low Energy • Includes Radar and television signals • Dangers: None

Radio Waves (cont.)

FM – Frequency Modulation • Measured in Megahertz (MHz)

AM – Amplitude Modulation • Measured in Kilohertz (KHz) • Can bounce off the ionosphere and be heard further than FM

Radio Waves (cont.) RADAR • Radio Direction And Ranging • Used to measure the speed and/or location of an object

• Baseball, weather, aircraft, cars

Microwaves

Microwaves • Low Energy • Common Uses: Telecommunications, Microwaves, Radar • Dangers: Can kill healthy cells, can affect people with pacemakers

Infrared Waves Infrared Waves • Low Energy • Common Uses: Heat Lamps, Night Visions Goggles • Dangers: Overexposure can cause burns

Infrared Waves in Astronomy

Ultraviolet Waves Ultraviolet Waves • High energy, Short wavelength, High Frequency • Common Uses: Sterilize medical equipment, helps skin produce vitamin D • Dangers: Can burn, cause skin cancer

Ultraviolet Waves in Astronomy

X-rays X-rays • High energy, Short wavelength,

High Frequency • Blocked by high density substances • Common uses: Medical, kill cancer cells, inspect baggage • Dangers: Kills healthy cells

Gamma Rays Gamma Rays • High energy, Short wavelength, High Frequency • Blocked by lead or concrete • Uses: Astronomy research • Dangers: Can damage healthy tissue

More About Electromagnetic Radiation • Electromagnetic radiation travels in space with no medium or may travel through a transparent (see-through) medium – Think visible light traveling through a window

• Electromagnetic radiation is a transverse wave. • Electromagnetic waves have an electric part and a magnetic part that are perpendicular to each other