Textbook Material to Read

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Chapter 16: Oscillatory Motion and Waves

16.1 Hooke’s Law: Stress and Strain Revisited

16.2 Period and Frequency in Oscillations

16.3 Simple Harmonic Motion: A Special Periodic Motion

16.9 Waves

Key Concepts

Definitions

Waves can be

• mechanical or
• electromagnetic.

A mechanical wave requires medium to propagate.

Example: waves on water.

An electromagnetic wave does not require medium to propagate.

Example: microwaves.

Waves can be

• transverse
• longitudinal.

A transverse wave is a moving wave whose oscillations are perpendicular to the direction of the wave.

Example: light.

Longitudinal waves are waves in which the displacement of the medium is in the same direction.

Example: sound.

Explanation and illustration

Watch this video to learn more about types of waves and waves characteristics.

Summary

• A wave is a disturbance that moves from the point of creation and carries energy but not mass.
• Mechanical waves must travel through a medium.
• Sound waves, water waves, and earthquake waves are all examples of mechanical waves.
• Light is not a mechanical wave since it can travel through a vacuum.
• Light is an electromagnetic wave.
• A periodic wave is a wave that repeats for several cycles, whereas a pulse wave has only one crest or a few crests and is associated with a sudden disturbance.
• Periodic waves are associated with simple harmonic motion.
• A transverse wave has a disturbance perpendicular to its direction of propagation, whereas a longitudinal wave has a disturbance parallel to its direction of propagation.

Hooke’s Law

[latex]F=-kx[/latex],

[latex]F[/latex] is the restoring force, [latex]k[/latex] is a constant related to the difficulty in deforming the system, [latex]x[/latex] is deformation.

Period and frequency

The time to complete one oscillation remains constant and is called the period [latex]T[/latex].

Frequency [latex]f[/latex] is defined to be the number of events per unit time.

For periodic motion, frequency is the number of oscillations per unit time. The relationship between frequency and period is

[latex]f=1/T[/latex]

SI units of frequency is Hz; SI units of period is s.

Wave equation: speed, frequency, and wavelength relationship

speed = frequency x wavelength

[latex]v=f*w[/latex]

frequency = speed / wavelength

[latex]f=v/w[/latex]

wavelength = speed / frequency

[latex]w=v/f[/latex]

This wave equation is true for all types of waves.

Additional Resources

1. OpenStax High School Physics, chapter 13 Waves and Their Properties

2. Introduction to Waves with Khan Academy

To Do

Work on

• • Introduction to Waves
  • Waves Characteristics
  • Quiz #1

3. Learn about the Wave Equation .