Two identical light waves, A and B, are emitted from different sources and meet

Question

Two identical light waves, A and B, are emitted from different sources and meet at a point P. The distance from the source of A to the point P is L_A, and the source of B is a distance L_B from P. Which of the following statements is necessarily true concerning the interference of the two waves? A and B will interfere constructively if L_A - L_B = m lambda, where m = 1/2, 3/2, 5/2, ... A and B will interfere constructively because their wavelengths are the same. A and B will interfere constructively because their amplitudes are the same. A and B will interfere constructively if L_A - L_B = m lambda, where m = 0, 1, 2, 3, ... A and B will interfere destructively if L_A > L_B

Explanation / Answer

From options B and C, it is implied that the waves are coherent i.e. identical which we already know from the given question, but the coherence doesn't always means constructive interference will occur. Hence option B and C are eliminated.

The constructive and destructive interference is decided by the diference between LA and LB, If their difference is an integer times their wavelength, there only the light waves will interfere constructively. Option D satisfies the given condition and hence the answer.

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.