Wave Properties and Graphs

U4L3: Wave Properties

MS-PS4-1. Use mathematical representations to describe a simple model for waves that includes how the amplitude if a wave is related to the energy of a wave.

MS-PS4-2. Develop and use a model to describe that waves are reflected, absorbed or transmitted through varius materials.

​Homework Check

Take out your homework folder. Open to the U4L2: Types of waves.

Match

Match the following

• Transverse Wave

• Longitudinal Wave

• Surface Wave

Particles of the medium move perpendicular to the

direction of the movement of the wave

Particles of the medium move parallel to the direction

of the movement of the wave.

Travels along the surface of a medium where particles

oscillate perpendicular and parallel

• Particles of the medium move perpendicular to the

  direction of the movement of the wave

• Particles of the medium move parallel to the direction

  of the movement of the wave.

• Travels along the surface of a medium where particles

  oscillate perpendicular and parallel

Open Ended

Compare and contrast transverse, longitudinal and surface.

Compare and contrast transverse, longitudinal and surface waves

All waves are created by vibrations. Transverse waves move perpendicular to the wave. Longitudinal move parallel to the wave. Surface waves move parallel and perpendicular creating a circular motion along a surface.

Draw

Draw a transverse wave

Draw

Draw a longitudinal wave

​Learning Outcomes

​Key Words

• Amplitude (波幅) bōfú

• Wavelength (波长) bōcháng

• Frequency (频率) pínlǜ

• Equilibrium (平衡) pínghéng

• Crest (波峰) bōfēng

• Trough (波谷) bōgǔ

• Period (波浪周期) bōlàng zhōuqī

Describe different properties of a wave.

1. Define amplitude, wavelength and velocity.

2. What is the relationship between frequency and period?

3. What is the relationship between velocity, wavelength and frequency?

4. Compare and contrast energy between high amplitude and low amplitude

Wave properties describe how waves move, and what they look like. Some properties are:

• Amplitude

• Frequency

• Wavelength

• Period

• Velocity (Speed)

​

​Wave Properties

• To best visualize the properties, we draw graphs of waves

• The horizontal axis (x axis) measure length or time

• The vertical axis (y axis) measures height

• The horizontal axis is equilibrium or the rest position. Points along the x axis represent rest or equilibrium.

​Wave Properties

• As a wave moves towards an area in the medium, particles in the medium move upward from their rest position. The maximum upward displacement is called a crest.

• As the disturbance moves away from that area, the particles move downward, past the rest position. The maximum downward displacement is called a trough.

​Wave Properties

• Amplitude is the height of the wave. The maximum displacement from rest.

• The larger the amplitude, the bigger the wave (Louder sound, bigger ocean wave, etc.)

• Waves with higher amplitude carry more energy

• To determine the amplitude of a wave on a graph, measure the distance from equilibrium to the top of a crest or trough. Do NOT measure the distance from trough to crest.

​Amplitude

• Wavelength is the length of one complete wave.

• Wavelength is represented with the Greek letter lambda (λ).

• Wavelength is usually measured in meters (m).

• To determine wavelength of a wave, measure the distance between two corresponding points on back-to-back wave cycles. Be sure the x axis is measuring distance.

​Wavelength

• The frequency of a wave is the number of times a wave cycles in one second.

• Frequency is measured in Hertz (Hz).

• To determine the frequency of a wave, count the number of wave cycles completed in one second. Be sure the x axis is measuring time.

​Frequency

• The period of a wave is the time it takes for a wave to complete one wave cycle.

• Period is measured in seconds (s).

• Period and frequency are related to each other

• Period is represented with a capital T.

• Frequency is represented with a lowercase f.

Period

• The velocity (v) or speed of a wave is the rate at which the wave moves through matter or across space.

• Velocity is measured in meters per second (m/s).

• You can calculate the velocity of a wave if you know the wave’s frequency and wavelength.

• To calculate velocity, use the equation:

velocity (v) = wavelength (λ) × frequency (f)

Velocity

Multiple Choice

What is wavelength?

• The length of one wave cycle

• The time it takes to complete one wave cycle

• The height of a wave

• The rate at which a wave moves

Multiple Choice

What is amplitude?

• The number of wave cycles a wave completes in one second

• The time it takes to complete one wave cycle

• The height of a wave from equilibrium (rest)

• The length of one wave cycle

Multiple Choice

If a wave completes 2 cycles in 1 second, what is the frequency?

• 1 Hz

• 1/2 Hz

• 1/4 Hz

• 2 Hz

Hotspot

Click on the line the represents amplitude

Hotspot

Click on the line the represents wavelength

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Physics Simulation: Simple Wave Simulator

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Complete your homework.

​You will be tested next class!

​Homework

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Open Ended

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Open Ended

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