Question

The reason for the phenomenon of interference is

• A. Phase difference
• B. Change in amplitude
• C. Velocity change
• D. Intensity change

Hint:

Remember that interference is all about how waves "line up". This alignment is described by their phase difference. A constant phase difference (coherence) is the key ingredient for creating a stable interference pattern.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Interference is a phenomenon in which two or more coherent waves (waves with a constant phase difference) superpose to form a resultant wave of greater, lower, or the same amplitude. The resulting intensity distribution is a modification of the individual wave intensities.
Step 2: Detailed Explanation:
The principle of superposition states that the resultant displacement at a point is the vector sum of the displacements due to individual waves.
- If the waves arrive at a point in phase (e.g., crest meets crest), their amplitudes add up, leading to constructive interference and maximum intensity.
- If the waves arrive at a point out of phase (e.g., crest meets trough), their amplitudes subtract, leading to destructive interference and minimum intensity.
The outcome of the superposition (constructive or destructive) at any point depends entirely on the phase difference between the waves arriving at that point. A constant phase difference is the necessary condition for a stable and observable interference pattern.
The other options are consequences or unrelated concepts:
(B) Change in amplitude is the result of interference, not the cause.
(C) Velocity change is related to refraction.
(D) Intensity change is also a result of interference, not its cause.
Step 3: Final Answer:
The fundamental reason for interference patterns is the constant phase difference between the superposing waves. Therefore, option (A) is correct.