Wave Properties Flashcards
Phase
A particular point in the cycle of the wave, measured in degrees, radians, or expressed in terms of pi.
Phase difference
It means to have the same frequency, but oscillate differently to each other.
How far a wave lags behind another wave in proportion to the wavelength. Measured in degrees or radians.
Coherence
Waves are coherent if they have the same frequency, wavelength, AND the same constant phase difference.
A Progressive wave
A progressive wave is an oscillation that travels through matter (or in some cases a vacuum),
transferring energy from one place to another, but not transferring any matter. The particles in
the matter vibrate as the wave passes through them, but they do not move along with the wave.
The two types of progressive waves
Transverse waves, where the oscillations are perpendicular to the direction of wave travel, such as electromagnetic waves and waves on the surface of water. The waves have peaks and troughs at the maximum and minimum points of displacement.
Longitudinal waves, where the oscillations are parallel to the direction of energy transfer, such as
sound waves. They have areas of compression, where particles are closer together, and areas of
rarefaction, where particles are more spread out.
More about phase difference
Phase difference is the difference in displacement of particles along a wave, or in 2 different
waves, measured in radians. If particles oscillate in step with each other, they are in phase, and
their phase difference will be a multiple of 2π.
If particles oscillate out of phase, then the equation (x divided by lambda) * 2 pi — where x is the separation between the two particles — can be used to calculate the phase difference.
When two particles are oscillating at a difference of pi, or half a wavelength out of step with each other, they are in antiphase.
Displacement
The distance from the equilibrium position in a particular direction.
Amplitude
The maximum displacement from the origin
Wavelength
The maximum distance between two adjacent points on a wave oscillating in phase
Period
The time taken for a full oscillation or one wavelength to pass a given point.
The equation is:
T = 1/f
T is the period of the wave
f is the frequency or the wave.
Alternatively it can be expressed as
T = lambda/v
Lambda = wavelength
v = the velocity of the wave
Frequency
The number of complete oscillations passing a given point per second.
f = 1/T
f also = v/Lambda
Wave speed
The distance travelled by a wave per unit time.
v = lambda*f
Harmonics
Points at a stationary wave that don’t change because the waves in each direction reinforce each other.
Threshold frequency equation
(Phi) work function divided by planck constant
What do you call it when an electron is completely removed from an atom?
Ionisation
