Waves 2 Flashcards
(15 cards)
What is the definition of Superposition?
When two waves of the same type meet, they pass through each other. Where the waves overlap or superpose they produce a single wave whose instantaneous displacement can be found using the principle of superposition of waves.
What is the principle of superposition?
When two waves, of the same type, meet at a point, the resultant displacement at that point is equal to the sum of the displacements of the individual waves.
What is Interference?
When two progressive waves continuously pass through each other they superpose and produce a resultant wave with a displacement equal to the sum of the individual displacement of the two waves.
What is constructive interference?
If the two waves are in phase superpose with another then this is called constructive interference.
They would create a resultant displacement with increased amplitude.
What is destructive interference?
If the two waves are in antiphase superpose with one another this is called destructive interference.
They would create a resultant displacement with zero amplitude or smaller than the individual wave.
What is the definition of Coherence?
Coherence refers to waves emitted from two sources having a constant phase difference.
In order to be coherent the two waves must have the same frequency.
To form a stable interference pattern the waves must be coherent.
When do waves constructively interfere?
At a maxima
When do waves destructively interfere?
At a minima
What is the definition of Path Difference?
The difference in distance travelled by two waves from their source to a specific point.
How do you know if the two waves have arrived at a specific point in phase?
(In regards to path difference)
If the path difference is zero or a whole number of wavelengths.
This produces constructive interference at this point.
The resultant wave at this point has maximum amplitude.
How do you know if the two waves have arrived at a specific point in antiphase?
(In regards to path difference)
If the path difference is any whole number of half wavelengths.(So 0.5 or 1.5 or 2.5 etc)
This produces destructive interference at this point.
The resultant wave at this point has minimum amplitude.
What is the definition of a stationary wave?
A wave which remains in a constant position with no net transfer of energy and is characterised by its nodes and antinodes.
How is a stationary wave formed?
A stationary wave forms when two progressive waves with the same frequency travelling in opposite directions are superposed.
What is the definition of a node?
As the two waves have the same frequency at certain points they are at antiphase.
At these points their displacement cancels out and this forms a node.
A point where the displacement is always 0.
What is the definition of an antinode?
As the two waves have the same frequency at certain points they are in phase.
At these points their displacements add up to form a resultant displacement.
A point of greatest amplitude and therefore intensity.
