Question

If a string wave encounters a completely fixed end, what happens to its phase?

(a) Stays the same

(b) Changes by π

(c) Changes by π/2

(d) Waves gets destroyed

I got this question in a national level competition.

Enquiry is from Reflection of Waves in chapter Waves of Physics – Class 11

Answer 1

Correct choice is (b) Changes by π

To explain I would say: The reason for the phase to change by π is that the boundary displacement should be zero because it is rigid & by principle of superposition it is only possible if the reflected wave differs by a phase of π.