Physics » Electromagnetic Waves

Electromagnetic Waves

Key Words

Transverse waves - the oscillations travel up and down.

Oscillations - vibrations.

Electromagnetic (EM) waves - transverse waves that transfer energy from a source to an absorber. They travel at the same speed through air or a vacuum. EM waves form a continuous spectrum over a range of frequencies.

Refraction -waves cross a boundary between materials, the angle is changed.

Optical density - how quickly light can travel through it.

Radio waves - made up of oscillating electric and magnetic fields. Types of radio wave:

  • Long-wave radio - wavelengths of 1-10km. Can be received at long distances, wavelengths bend around the curved surface of the earth.
  • Short-wave radio - wavelengths of 10m-100m. Can be received at long distances. They reflect from the ionosphere.
  • Bluetooth - uses short-wave radio waves.
  • Medium-wave - reflect from the ionosphere.

Microwaves - used by satellites. Signal from a transmitter is transmitted into space, received by the satellite and bounced back down to earth.

Infrared Radiation - given out by all hot objects. Can be used to increase or monitor the temperature.

Optical fibres - thin glass or plastic fibres that can carry data over long distances.

Ultraviolet Radiation (UV) - found naturally in sunlight.

X-rays - pass easily through flesh but not so easily through denser material like bones or metal.

Gramma Rays - used in medicine in patients to kill cancer cells.

Black body - an object that absorbs all of the radiation that hits it.

 

Also see Waves, Atoms & Radiation,

 

EQUATION Wave Speed

PRACTICAL
Infrared Radiation

Watch the video and have a go at writing out the steps of the practical.

Note paper for practical