What happens when two waves meet while they travel through the same medium? What effect will the meeting of the waves have upon the appearance of the medium? Will the two waves bounce off each other upon meeting or will the two waves pass through each other?
Wave Interference occurs when two waves meet while traveling along the same medium. To begin our exploration of wave interference, consider two pulses of the same amplitude traveling in different directions along the same medium.
1. Predict what will happen in the following situation. Sketch your prediction:
PART 2. PRINCIPLE OF SUPERPOSITION
To determine the resultant wave we can use the Principle of Superposition:
“When two waves interfere, the resulting displacement of the medium at any location is the algebraic sum of the displacements of the individual waves at that same location.”
1. For each of the cases on questions 1, 3, 4 and 6 find the amplitude of the resultant wave if each square represents one cm.
Q1. _________Q3. _________
Q4. _________Q6. _________
2. To determine the precise shape of the medium at a given instant in time, the principle of superposition must be applied to several locations along the medium. In this example several locations have been labeled. Use the principle of superposition for each location and mark the resultant amplitude with a dot. Neatly connect the dots to find the resultant waveform.
3. Several positions along the medium are labeled with a letter. Categorize each labeled position along the medium as being a position where either constructive or destructive interference occurs.
1. Sound is a pressure wave that consists of compressions and rarefactions. Explain constructive interference of two sound waves in terms of pressure variations.
2. A friend tells you that the word destructive tends to imply that the energy as well as the form of the waves is destroyed. Do you agree with your friend? Explain your answer.