Chapter 12 Flashcards
What is superposition?
When 2 waves meet, the total displacement at a given point in time is the vector sum of the 2 individual displacements
What happens if the waves meet in phase?
Maximum positive displacements of each sum if waves meet in phase. This is constructive interference
What happens if waves meet in anti phase?
Maximum positive displacement of one wave sums with maximum negative displacement of other wave. Destructive interference
Why can’t the superposition of waves always be observed?
It only works if there are 2 coherent sources.
Coherent wave sources are those which maintain a constant phase difference at a given point throughout time
What is the type of coherency?
Temporal coherency-wave sources have the same frequency
What is the PLD?
Difference in length in the paths travelled by each wave.
For 2 coherent wave sources, its the fraction of the wavelength of the wave which directly correlate with the phase difference between the waves
What does the PLD indicate?
Even multiple of lamda/2 is constructive
Odd multiple of lamda/2 is destructive
What is a stationary wave?
Wave that oscillates but does not transfer any energy
How does a stationary wave occur?
When 2 waves of the same frequency move in opposite directions and superpose
The amplitude of a stationary wave at a given point in space is constant in time
What are nodes and anti nodes?
Nodes-point of zero displacement, antiphase
Anti nodes- point of maximum displacement, in phase
