Radio waves, microwaves, infra red and visible light can be used for communication.
Radio waves are used to transmit __________ and __________ programmes between different points on the Earth’s surface. Longer wavelength radio waves are __________ from an electrically charged layer in the Earth’s upper atmosphere, called the __________.
This enables 'information' to be sent between distant points despite the curvature of the Earth’s surface.
Microwaves can pass through the Earth’s atmosphere and are used to send information to and from __________ and within mobile phone networks. Microwave radiation has wavelengths that are strongly absorbed by water molecules and can also be used for __________.
Infra-red (same as we discussed for heat ) is used for short range communication through air. It is used for remote controls and IrDA ports on mobile phones, computers and printers.
Infrared is also what is used to grill and toast food. Human skin can feel it, but too much and the skin will burn.