Uses of EM Waves (Oxford AQA IGCSE Physics)

Uses of EM Waves

• Electromagnetic waves have a variety of uses and applications

Table of Applications of EM Waves

Radio Waves

• Radio waves and microwaves share a lot of similarities and applications

  • Their main uses are in wireless communications

• Radio waves can be used to transmit signals over short distances 

• Radio station signals are transmitted at a longer wavelength than terrestrial television signals

• Bluetooth uses radio waves instead of wires or cables to transmit information between electronic devices, over short distances, such as phones and speakers

Microwaves 

• Microwaves can be used to transmit signals over large distances 

• On the ground, mobile phone signals use a network of microwave transmitter masts to relay the signals from the nearest mast to the receiving phone 

• Certain frequencies of microwaves are absorbed by water molecules, therefore high intensity microwaves can be used for heating substances that contain water such as food

Infrared

• Infrared is emitted by all objects and can be detected using special cameras (thermal imaging cameras). These can be used in industry, in research and also in medicine

• Security cameras and baby monitors are capable of seeing slightly into the infrared part of the spectrum and this can be used to allow them to see in the dark

  • Infrared lights are used to illuminate an area without being seen, which is then detected using the camera

• Remote controls also have small infrared LEDs that can send invisible signals to an infrared receiver on a device such as a TV

• Infrared travels down fibre optic cables more efficiently than visible light, and so most fibre optic communication systems use infrared

Visible Light

• Visible light is the only part of the electromagnetic spectrum that the human eye can see

• Cameras also detect visible light for use in photography and filmography

• Visible light can also be used for fibre optic communications

  • This is because glass is transparent to visible light

  • Visible light (and infrared) can carry high rates of data due to their high frequency

  • This makes them suitable for transmitting television and high-speed broadband signals

Ultraviolet

• Ultraviolet is responsible for giving you a sun tan, which is your body’s way of protecting itself against the ultraviolet

• When certain substances are exposed to ultraviolet, they absorb it and re-emit it as visible light (making them glow)

  • This process is known as fluorescence

  • Fluorescence can be used to secretly mark things using special ink

  • Most banknotes have invisible fluorescent markings on them

• Fluorescent light bulbs also use this principle to emit visible light

X-rays

• The most obvious use of x-rays is in medicine

• X-rays can pass through most body tissues but are absorbed by the denser parts of the body, such as bones

  • When exposed to X-rays, the bones absorb the X-rays, leaving a shadow which can be seen using a special X-ray detector or photographic film

Gamma Rays

• Gamma rays are very dangerous and can be used to kill cells and living tissue

• This property can be utilised in both cancer detection and treatment 

  • If these gamma rays are carefully aimed at cancerous tissue, they can be very effective at destroying the cancerous cells

• Gamma rays can also be used to sterilise food and medical equipment by killing bacterial cells