Energy P5

Waves Transfer energy from one place to another without transferring any matter

An example of this could be if you drop a twig into a calm pool ripples will appear but they wont carry the water or the twig away with them.

When Waves travel through a medium they make the particles of the medium vibrate.

The particles transfer energy between them as they vibrate.

Words to describe waves 

Displacement  the distance btween a point on the wave and the rest position.

Amplitude  The displacement of a wave from the rest position to a crest or trough

Wavelength  The distance from one point  on the wave to the same point on the next wave

frequency The number of complete waves passing a certain pointt each second this is measured in herts (Hz)

Period The time it takes for one complete wave to pass a certain point  Period = 1 divided by frequenc

Transverse Waves 

The vibrations are perpendicular (at a right angle) to the direction the waves travels. e.g ripples on water are transverse. They cant travel through liquid 

Longitudal Waves 

Vibrations are in the same direction as the direction of the wave travels e.g sound waves. 

Longitudal waves squash up and stretch out the arrangement of particles in the medium.

Wave Speed equation 

An Oscilloscope is used to find the speed of sound.

1) Connect a signal generator to a speacker. this will let you generate sound with a set frequency.

2) Connect two microphones to an oscilloscope (which shows waves on a screen)

3) Set up so that the waves are shown as seperate waves

4) slowly move one microphone away until the two waves are lined up

5) measure the distance between the microphones with a ruler to find on wave lenght

Reflection

Reflection is when waves bounce back 

One rule for all reflection:

Angle of incident = Angle of reflection.

Refraction

Refraction is when waves change direction at the boundary

The normal is an imaginary line that is perpendicular to the boundry.  

The angle of incident is the angle between the incoming and the normal

The angle of refraction is the angle between the refraction ray and the normal

How a wave refracts depends on the material it travels between

 You can use  rectangular glass blocks to investigate refraction of light 

 As you increase the angle of incident the angle of refraction increases too.

Light is an electromagnetic wave. All electromagnetic waves can be refracted.

Elecromagnetic Waves (EM)

There is a spectrum of EM waves

Em waves can travel through space where there are no particles, they travel at the same speed (3000000000m/s through air or space.  they vary in wavelength and frequency. Those with shourter wave lengths have a higher frequency. There are EM waves of every wavelength in a certain range.  this is known as  continuous spectrum.

the spectrum is split into 7 gropups based on length of wave and frequency.

 Our eyes can only detect  a small part of the EM spectrum.

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