Two Source Interference Flashcards
What are coherent waves?
Waves with the same phase difference constantly and the same wavelength/frequency
When does interference happen?
When any two waves superimpose on one another
What is the degree of constructive and destructive interference dependent on?
On much further one wave is in front of another (path difference)
When do you get constructive interference and a maxima?
When there are points an equal distance from two sources in phase
OR
When the path difference is equal to a whole number of wavelengths
When do you get total destructive interference and a minima?
When the path difference is equal to have a wavelength - the waves are out of phase
What is path difference and what is it measured in?
Actual measurable difference in distance that two waves travel from a source to a common point
Measured in wavelength
What is phase difference and what is it measured in?
A fraction of a cycle between the oscillation of two points
Measure in radians
What is the path difference of constructive interference?
n x wavelength
What is the path difference of destructive interference?
(n + 1/2) x wavelength
OR
n/2 x wavelength
What is interference?
When two coherent waves pass through each other
How do we create coherent source (light and sound)?
Light - Shine a beam of light through a double slit
Sound - play the same sound from two speakers
What spots do constructive and destructive interference cause?
Constructive - bright/loud
Destructive - dull/quiet
What is the equation for wavelength in terms of slit difference?
wavelength = ws/D w = fringe width s = slit seperation D = distance from slit to screen
What must the relationship between D and s be for the equation to work?
D»s
D needs to be a lot bigger than s
What is the relationship between SinO and TanO?
Close enough
small angle approximation - less valid with greater angles
