Waves Flashcards
Continuous Wave definition
Constant amplitude and frequency
Wavelength definition
The distance between any point and the next identical point
Frequency definition
Number of oscillations in one second
Measured in Hz
Frequency and Time equation
f = 1/T
Speed/Frequency/Wavelength equation
c = f * wavelength m/s = Hz * m
Dispersion definition
Waves separate out whilst travelling through a medium
Due to different wavelengths travelling at different speeds
Displacement definition
Distance from the centre of the oscillation to the particle
Vector, so can be negative
Amplitude definition
Maximum displacement
Energy/Amplitude equation
Energy is directly proportional to amplitude squared
E = k A^2
Out of phase definition
Two waves with same frequency and wavelength, but one is shifted compared to the other
Single slit diffraction pattern
Central maxima
Decreasing height of maxima as you get further from centre
Double slit interference
How to increase fringe separation
Distance from slits to screen is increased
Wavelength of light used is increased
Slit spacing (distance between centres of slits) is decreased
Fringe separation equation
w = λD/s w = fringe separation λ = wavelength of light D = distance from slits to screen s = slit spacing
Slit spacing definition
Distance between centres of slits
Why are fringes formed
Interference of light
Why are bright fringes formed from double slit
Light waves from each slit are in phase
Path difference = lambda
Why are dark fringes formed from double slit
Light waves from each slit arrive 180º out of phase
path difference = lambda/2
Why are lasers used in double slit experiments
Coherent source of light => no need for a single slit before.
Photons in a laser beam are in phase with each other
Highly monochromatic, meaning its wavelength can be calculated to within a nanometre
What happens when white light is used for double slits
Central fringe is white
Each component colour of white light produces its own fringe pattern
Each pattern is centred on the screen at the same position
Principle of superstition
Exact moment when 2 waves meet Crest + crest = super crest Trough + trough = super trough Crest + trough = 0 displacement - If waves aren't of equal magnitude, crest + trough = minimum
In phase definition
Two waves superimpose constructively
Anti phase definition
two waves superpose destructively
Node definition
Resultant wave = 0 displacement
No oscillation
Anti-node definition
Resultant waves has largest amplitude
Maximum oscillation