3.3 Physics Waves

Fill in the gaps: T_____ waves have particles that move __________ to the direction of the wave

Transverse waves have particles that move at right angles to the direction of the wave

Fill in the gaps: L_____ waves have particles that move __________ to the direction of the wave

Longitudinal waves have particles that move parallel to the direction of the wave

What is superposition?

Superposition is the resultant wave of multiple waves being at the same place at the same time, so is the vector sum of the individual waves.

What is diffraction?

Diffraction is the radiating out of wavefronts as they pass around a barrier or move through a gap.

When does constructive interference occur?

When 2 peaks or 2 troughs arrive at the same point at the same time and are in phase.

When does destructive interference occur?

When a peak and trough arrive at the same point at the same time and are out of phase.

What does it mean if two waves are coherent?

It means they have the same amplitude and frequency and are always exactly in phase.

What is the equation for beat frequency?

F_b= | F₁-F₂ |

What are beats?

Beats are the periodic and repeating loud and soft sounds heard when two sound waves of slightly different frequencies interfere with each other.

Fill in the gaps:
Explain why beats form-

When 2 ____ waves of slightly different __________ ________, ___________ regions of __________ and _________ interference cause a ________ and ________ ______.

When 2 sound waves of slightly different frequencies combine, alternating regions of constructive and destructive interference cause a periodic and repeating pattern.

What are nodes?

Nodes are points on a standing wave that are always at rest (skinny point)

What are antinodes?

Antinodes are points in a standing wave with the greatest displacement (fat point)

The distance between 2 adjacent nodes (or antinodes) is=

half the wavelength

What is the general frequency equation for standing waves on strings and waves in fully open pipes?

f_n=nv/2L where n= the number harmonic

Name the pairs of names for the first 3 possibilities for standing waves on strings and waves in fully open pipes:

Fundamental- 1st harmonic

1st overtone- 2nd harmonic

2nd overtone- 3rd harmonic

Name the pairs of names for the first 3 possibilities for standing waves in half-open pipes:

Fundamental- 1st harmonic

2nd overtone- 3rd harmonic

4th overtone- 5th harmonic

For standing waves on a string what is the same as the number of the harmonic?

The number of anodes

For waves in fully open pipes what is the same number as the number of the harmonic?

The number of nodes

for standing waves on strings and waves in fully open pipes, λ=

2L/n

For waves in half open pipes what is the same number as the number of the harmonic?

The number of nodes + number of anodes - 1

What is the general frequency equation for waves in halfopen pipes?

f_n=nv/4L where n= the number harmonic

For waves in half open pipes, λ=

4L/n