Waves 2 Flashcards
How does noise cancelling headphones work?
Microphon on outside detect background noise, speakers inside produce waves to cancel background waves
State The Principle of Superposition.
When two waves meet at a point, the resultant displacement is equal to the sum of the displacements of the individual waves.
What does it mean if waves superpose?
When two waves of the same type overlap and produces one wave.
When does intereference occur?
When waves superpose.
What is constructive interference?
In-pase waves superpose to create a wave with increased amplitude.
What is destructive waves?
When anti-phase waves superpose to create a resultant displacement that cancels each other out completely or partially.
What happens to intensity if amplitude increases by factor 2?
Increase by factor 4.
What is an intereference pattern?
A pattern of constructive and destructive interference formed as waves overlap.
What happens to the interference pattern if the waves are not coherent?
Pattern will change overtime and does not stay constant.
What does it mean if the waves are coherent?
Constant phase difference, same wavelength, same frequency.
What are maxima points?
where waves superpose constructively.
What are minima points?
Where waves supoerpose destructively.
What is path difference?
In relation to wavelngth, the difference between the distances travelled bu two waves starting and arriving at the same point.
What ranges would the path difference of antiphase waves be?
3/2 pie, 5/2 pie etc
What is phase difference?
The difference in the phases of two waves of the same frequency
If the phath difference is 2landa what is the phase difference?
4pie
Is the phase difference is 3pie what is the path difference?
3/2landa
What is monochromatic waves?
All waves have same wavelength.
If it is not monochromatic light what do you do?
Use a colour filter or single slit
Describe the double slit experiment.
- Light leaves source
- Hit single light, diffraction, circular wavelength move out
- Diffract at double slits
- Waves overlap and interefere
- Intereference pattern with fringes
What are fringes in terms of light?
Alternating light and dark bands.
What is a, d and x?
a - distance between the slits
d - distance between slits and screen
x - distance between fringes
What is the formula to find landa?
Landa = ax/D
Formula for energy and power
E = Pt
