Superposition Flashcards
Principle of Superposition
The Principle of Superposition states that when two or more waves of the same kind MEET AT A POINT at the same time, the DISPLACEMENT of the resultant wave is the VECTOR SUM OF THE DISPLACEMENTS of the individual waves at that point in time.
Diffraction
It is the spreading of waves at an edge or through a slit so that the waves do not travel in straight lines.
Coherence
Coherent waves have constant phase difference.
Conditions for 2-source interference fringes to be observable
1) Waves meet/overlap
2) Waves have constant phase difference (are coherent
3) Waves have equal or approximately equal amplitudes
4) Transverse waves must either be unpolarized or polarized in the same plane.
5) Slit separation d is a few times of wavelength lambda
Interference
It is an effect that occurs when two or more waves overlap to produce a new wave pattern.
Constructive interference
When two waves meet in phase and the resultant amplitude is the sum of the individual amplitudes of the waves.
Destructive interference
When two waves meet out of phase and the resultant amplitude is the difference of the amplitudes of the waves.
(If the amplitudes of the two waves are the same, we obtain complete destructive interference)
Stationary waves
When two progressive waves of the same type of equal amplitude, equal frequency, equal wavelength, equal speed travelling in opposite directions meet and undergo superposition with each other, a stationary wave is formed.
Antinode
A point on a stationary wave vibrating with maximum amplitude.
Node
A point on a stationary wave vibrating with zero amplitude.
Rayleigh criterion
For the diffraction patterns to be just resolved, the central maximum of one pattern must lie on the first minimum of the other pattern. (angle from observer greater or equal to lambda/b)
