The Use of Waves and Universe Expansion – Visible light, Infra red, Radio and Microwaves

The Use of Waves and Universe Expansion – Visible light, Infra red, Radio and Microwaves

The light we can see is known as visible light. It’s a very useful way of communicating with each other, like through literature, photography or video. Unlike sound waves, the transmitter and the receiver must be in each other’s line of sight.

Very bright light, the Sun being a prime example, can damage the eyes and shouldn’t be looked at directly.


Infra red

It’s not possible for humans to see infra red radiation but it can be felt as heat energy. It has a number of uses:

  • – heaters
  • – toasters
  • – grills
  • – sensors for security lights and burglar alarms
  • – television and DVD remote controls
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Radio waves

Radio waves are what people use to transmit radio and television programmes. Television, however, requires higher frequencies than radio.

In order for a radio programme receiver to pick up a signal it doesn’t have to be directly in view of a transmitter. Diffraction means that radio waves are able to travel past obstructions like hills. However, a better quality signal is ensured by building repeater stations.

Very low frequency waves are also reflected from the ionosphere. The ionosphere is a layer of the upper atmosphere which is electrically charged. Due to the curvature of the surface of the Earth these radio waves can reach receivers located far away.



Microwave radiation is also used to transmit signals. Mobile phone use microwaves. Microwave transmitters and receivers, which are located on masts and various buildings, are able to communicate with mobile telephones but only within their range.

Microwave radiation travelling at particular wavelengths are able to travel out of the Earth’s atmosphere. These are used to communicate with satellites orbiting in space. For example, this is how satellite television works.

Some people have health concerns regarding the use of mobile phones. They think that microwaves could damage tissue in the body. However, others argue that the microwave intensity is too low and that microwave radiation isn’t ionising so can’t cause cancer.