Necessary condition for obtaining an interference pattern when light waves (of same frequency) from two points S₁ and S₂ superpose is:

Intensity of two waves

Phase difference between the two waves at S₁ and S₂ must be

1)

Must be equal

Zero

2)

Must be equal

π

3)

Must be equal

Constant with time but not necessarily zero

4)

Need not be equal

Constant with time but not necessarily zero

Question

Question

This question was previously asked in

RSMSSB Lab Assistant 2016 Official Paper

Answer 1

Concept:

The superposition principle simply states that when two or more waves overlap in space, the resultant wave is equal to the algebraic sum of the individual waves.
Necessary conditions for superpose is that waves should be in the same frequency, the Direction of waves or phase angle should also be the same, and the amplitude of both waves should also same.

F3 Madhuri Engineering 02.05.2022 D8

Here one example is shown in the figure where Y₁ and Y₂ are two waves with the same frequency and different amplitudes make the Resultant wave Y.

	Intensity of two waves	Phase difference between the two waves at S₁ and S₂ must be
1)	Must be equal	Zero
2)	Must be equal	π
3)	Must be equal	Constant with time but not necessarily zero
4)	Need not be equal	Constant with time but not necessarily zero