# Condition for generating a stable interference pattern Coherent waves are two circular waves of same frequency, wavelength, amplitude and phase.

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Condition for generating a stable interference pattern Coherent waves are two circular waves of same frequency, wavelength, amplitude and phase

Coherent sources Coherent sources are the wave sources that produce coherent waves

Constructive interference I When a crest meets a crest, the two waves reinforce each other

Constructive interference II When a trough meets a trough, the two waves reinforce each other

Destructive interference When a crest meets a trough, the two waves cancel each other

X Path difference Path difference at X ＝ |S 1 X - S 2 X|

Constructive interference Path difference = n, n = 0, 1, 2, …

Destructive interference

Antinodal lines (A) Antinodal lines : lines that link up the points of constructive interference of the same path difference

Nodal lines (N) Nodal lines : lines that link up the points of destructive interference of the same path difference

Increase the density of nodal and antinodal lines increase the separation of two sources

Increase the density of nodal and antinodal lines decrease the wavelength

Interference and energy redistribution According to the law of conservation of energy, energy cannot be created nor destroyed Interference is just a process of energy redistribution  energy at the points of destructive interference energy at the points of constructive interference

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