Waves Flashcards
Principle of superposition
When two or more waves meet the resultant wave can be found by adding the displacements of each wave.
Constructive interference
When two waves have the same amplitude and are travelling in phase the amplitude of the resultant wave will be twice that of the individual waves
Destructive interference
When two waves are in antiphase they will cancel each other out and the resultant will have an amplitude of 0
Coherent
When two waves have constant phase difference
Phase difference
Difference in the phases of two waves of the same frequency. (Measured in radians)
Path difference
Difference between the distances travelled by two waves arriving at the same point. (Measured in wavelength)
Wavelength= ax/D
a - slit separation
x - fringe separation
D - distance from slit to where the light is projected
Intensity
Power divided by area
Wm^-2
What happens when refraction occurs
Wave speed changes
Change in direction
Diffraction
When waves meet an obstacle or aperture they change direction
Radio waves wavelength
10^-1 — 10^4
Microwave wavelength
10^-4 — 10^-1
Gamma wavelength
10^-16 — 10^-9
X-rays wavelength
10^-12 — 10^-7
Refractive index
In a vacuum (=1)
Speed of light in a vacuum / speed of light in material
3x10^8
