12.1 Superposition of waves

Question 1

What is the principle of superposition?

Answer 1

When two waves meet at a point, the resultant displacement at that point is equal to the sum of the displacements of the individual waves.

Question 2

What is interference?

Answer 2

When two progressive waves continuously pass through each other they superpose and produce a resultant wave with a displacement equal to the sum of the individual displacements from the two waves.

Question 3

What is constructive interference?

Answer 3

If the two progressive waves are in phase then the maximum positive displacements (peaks) from each wave line up, creating a resultant displacement with increased amplitude.

Question 4

What is destructive interference?

Answer 4

• If the two progressive waves are in anti-phase then the maximum positive displacement (peak) from one wave lines up with maximum negative displacement (trough) of the other
• The resultant displacement is smaller than for each individual wave.
• If they have the same amplitude, the resultant wave will have zero amplitude.