Electromagnetic Spectrum

(shortest to longest wavelength)

Gamma rays, X-rays, Ultraviolet, Visible light, Infrared, Microwaves, Radiowaves

• Shortest wavelength = Highest frequency
• All EM waves transfer energy
• EM waves travel at the same speed in a vacuum
• All EM waves are transverse waves

Wave speed = Wavelength x Frequency

Speed = Distance/Time

Gamma - Most ionising as they have the most energy. Kills cancer cells and sterilises medical equipment or food.

X-rays - Ionising which can lead to cancer. Medical imaging and airport security

Ultraviolet - Can ionise cells in the body, leading to skin cancer. Sun tan beds, detecting forged bank notes

Visible light - Photosynthesis, vision

Infrared (thermal radiation) - Thermal imaging, remote controls

Microwave - Bluetooth signals, cooking, mobile phones

Radio - Radio and television signals

Causes particles to become charged (ions) as it passes through materials

• Gamma rays - Death
• X rays - Cancer
• Highest part of ultraviolet - Skin cancer and blindness

Optical fibres: Uses light to carry information. Light travels by Total Internal Reflection

• Draw with a ruler
• Changes direction at boundary
• Follows law of reflection
• Arrows to show direction of travel

Wireless: Uses light, infrared, radiowaves or microwaves

Satellite: Ground stations send and recieve microwave signals to and from manamde satellites which are in orbit around the Earth

Geostationary orbits

• Take 24 hours to orbit Earth so satellite remains above the same point of the Earth's surface.
• Worldwide communication = 3 geostationary orbits