Look at the data booklet: Look at the data booklet:
Look at the data booklet: Look at the data booklet:
Damping is when the oscillating system has to work against an external force
from for example friction or air resistance.
4.2 Energy and harmonic motion
Note that total energy do not depend on time or displacement because it is constant and
always the same whatever the time or displacement is.
4.3 Forced oscillations
Natural frequency: The frequency of the system when no external force is put on the system when it is oscillating.
Forced oscillation: When an external force is put on the system to force it to oscillate at a different frequency than
the natural frequency
Resonance: an increase in amplitude when a system is forced to oscillate at its own natural frequency.
Oscillators that are in phase move together
4.4 Wave characteristics
The pulse is short while the wave is long:
Interference is when pulses are combined to give a smaller or larger pulse. When the pulse is larger one has constructive interference and when the pulse becomes smaller one talks about destructive interference.
The period (T) is the time it takes for one complete wave to pass a fix point. Unit: s.
The frequency (f) is the number of complete cycles that pass a fix point per second. Unit: Hz = 1/s.
f = 1/T
Look at the data booklet:
Velocity = distance / time
v = λ / T
The displacement-position graphs show the position of all the points in the wave at a particular time
(it is a snapshot of the wave):
The displacement-time graphs show how the position of one point of the wave move with time:
Sound or the wave in a spring:
4.5 Wave properties
1. The incident angle = the reflected angle
2. the incident and reflected rays are in the same plane as the normal.
Reflection is when the wave hits a solid medium that the wave cannot continue in.
Refraction is the change of direction when a wave move from one medium to another.
When a wave goes from one medium to another the frequency (and period) will NOT change.
Amplitude, wavelength and velocity will change.
Normal light from a lamp or the sun is called white light and it is a mixture of light with different
wavelengths.
Each wavelength of light corresponds to a particular colour. The light that the eye can see varies from
400 nm (blue) to 800 nm (red). 1 nm = 10-9m.
The intensity of light (its amplitude) tells us who bright the light looks to an eye.
Light is a form of electromagnetic radiation and this radiation can have very different wavelengths corresponding
to different types of waves:
The speed of light = 3•108 m/s (can be found in the data booklet)
The speed of sound = 330 m/s