Reflection of Waves

• Key concept: Reflection is the bouncing back of waves from a surface.
• Mnemonic: Think of a ball bouncing off a wall. The ball represents the wave, and the wall represents the surface.
• Example: When you throw a ball at a wall, it bounces back at the same angle it hit the wall. This is an example of reflection.

Superposition of Waves

• Key concept: Superposition is the combining of two or more waves to produce a new wave.
• Mnemonic: Imagine two people pushing on a swing. If they push in the same direction, the swing will go higher. If they push in opposite directions, the swing will go lower. This is an example of superposition.
• Example: When two waves meet, they can either interfere constructively or destructively. Constructive interference occurs when the waves are in phase, and destructive interference occurs when the waves are out of phase.

Standing Waves on a String

• Key concept: Standing waves are formed when two waves of the same frequency and amplitude travel in opposite directions on a string.
• Mnemonic: Imagine a string tied to two fixed points. If you pluck the string, it will vibrate and create a standing wave. The nodes are the points where the string does not move, and the antinodes are the points where the string moves the most.
• Example: Standing waves can be seen on a guitar string when it is plucked. The nodes are the points where the string touches the frets, and the antinodes are the points where the string is free to vibrate.

Frequencies of Standing Waves on a String

• Key concept: The frequencies of standing waves on a string are determined by the length of the string, the tension in the string, and the mass per unit length of the string.
• Mnemonic: Imagine a guitar string. If you make the string longer, the frequency of the standing waves will decrease. If you increase the tension in the string, the frequency of the standing waves will increase. If you increase the mass per unit length of the string, the frequency of the standing waves will decrease.
• Example: The different notes on a guitar are produced by different standing waves on the strings. The longer the string, the lower the note. The higher the tension in the string, the higher the note. The thicker the string, the lower the note.