Question

If we have two coherent sources S₁ and S₂ vibrating in phase, then for an arbitrary point P constructive interference is observed whenever the path difference is ______.

Options

• An even multiple of wavelength

• An odd multiple of wavelength

• A fraction of a wavelength

• An integral multiple of wavelength

Answer 1

If we have two coherent sources S₁ and S₂ vibrating in phase, then for an arbitrary point P constructive interference is observed whenever the path difference is an integral multiple of wavelength.

Explanation:

If we have two coherent sources S₁ and S₂ vibrating in phase, then for an arbitrary point P whenever the path difference,
S₁P ~ S₂P = nλ (n = 0, 1, 2, 3,...), we will have constructive interference.