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

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 fixed end it exerts an equal and opposite downward force on the string. It results an inverted pulse or phase change of . 

Crest (C) reflects as trough(T) and vica-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.