Standing and Progressive Waves – Practice
1) Can a standing wave be produced in a string without reflection occurring? Explain your answer:
2) Compare the speeds of incident and reflected waves in a medium:
3) Why is there always a node at the fixed end of a string or rope?
1) No. Standing waves form in strings when two waves superimpose on each other.
For the superposition to occur, the waves must be travelling in opposite directions. Therefore, there must be reflection of the original wave to interact with the second wave.
2) The incident and reflected wave will travel at the same speed.
3) The reflected wave from a fixed point is always 180° out of phase (upside down)
At the fixed point, the displacement due to the incident wave will always be equal to the displacement of the reflected wave, but opposite in direction.
At any time, the superposition of these two waves results in zero displacement