Reflection And Transmission Of Waves On A String MCQ - Practice Questions with Answers

When waves are incident on a boundary between two media a part of incident waves returns back into the initial medium ( reflection ) while the remaining is partly absorbed and partly transmitted into the second medium ( refraction ).

Boundary conditions:

Assuming no transmission, no absorption and energy lost when a wave hits the boundary.

1. Rigid end: when the incident wave reaches a fixed end, it exerts an upward pull on the end, according to Newton's 3rd law at a fixed end it exerts an equal and opposite downward force on the string. It results in an inverted pulse or phase change $\pi$.

Crest (C) reflects as a trough( $T$ ) and vice-versa, Time changes by $\frac{T}{2}$, and path changes by $\frac{\lambda}{2}$.

2) Free end: when a wave or pulse is reflected from a free end, then there is no change of phase (as there is no reaction force).

crest (C) reflects as the crest (C) and trough (T) reflects as a trough(T), Time changes by zero, and path changes by zero.