Physics - EM Spectrum

Frequency is measured in Hertz ( Hz ).

Refraction is when waves pass into the new material but changes the direction it's travelling.

You can describe waves as being transverse or longitudinal.

All electromagnetic waves are transverse.

Reflection is when the waves bounce off a material.

Amplitude is the height of a wave.

The symbol for wavelength is Lambda.

Two examples of transverse waves are ripples on water and waves on string.

When light waves hit a black object they're absorbed and turned into heat.

A wavelength is the length of one complete wave. This can be from the top of one wave to the same point of the next or the bottom or side of a wave to the same point on the next wave. It is measured in meters and has the symbol lambda.

All objects are continually emitting and absorbing EM radiation over a range of wavelengths.

The speed of light is 3x10 (to the power of 8) m/s.

A transverse wave is a moving wave that consists of oscillations occuring 90 degrees to the direction of energy transfer.

The frequency of a wave is counted as the number of waves that pass a point per second.

Transmitting is when a wave is transmitted, the wave passes through the material and is not absorbed or reflected.

Waves transfer energy and information.

In longitudinal waves, the vibrations are along the same direction as the direction of travel.

Wavelengths are measured in meters.

The units for wavespeed are meters per second (m/s).

The velocity of a wave can be calculated from its wavelength and its frequency.

velocity = frequency x wavelength

v = f x lambda

The intensity of the different wavelengths depends on the objects temperature. As the temperature of an object increases, the intensity of every emitted wavelength increases - hot objects shine more brightly! 

Oscillating electric currents produce an oscillating electromagnetic field. Some of these fields take the form of an electromagnetic wave (which itself oscillates). When a radio wave reaches an antenna the oscillating electric current in the antenna which can then be amplified and decoded.

Different substances may absorb, transmit, refract, or reflect electromagnetic waves in ways that vary with wavelength. E.g. solar radiation.

1. Radio waves

2. Microwaves

3. Infared 

4. Visible light 

5. Ultraviolet 

6. Xray

7. Gamma rays

This is the order of the EM spectrum. 1 being not dangerous and 7 being very dangerous!

Radiation can cause changes in atoms. Some parts of the electromagnetic spectrum can cause atoms to become ions. Changes in the nuclei of atoms can produce gamma radiation. When materials are heated, they can produce visible light or infared radiation.