Waves and Sound Interaction - Lesson 2

Module L: Waves and Their Applications

• This module covers waves and their applications.

Unit 1: Waves

Day 1 - Lesson 2: Behavior of Waves - Sound Wave Interaction

• Standards:
  • MS-PS4-1: Use mathematical representations to describe a simple model for waves, including how amplitude relates to energy in a wave.
  • MS-PS4-2: Develop and use a model to describe how waves are reflected, absorbed, or transmitted through various materials.
• Objectives:
  • Identify the meaning of absorption, reflection, transmission, and define echo.
  • Explain how sound is reflected.
  • Compare and contrast reflection and transmission.

Vocabulary

• Absorption
• Reflection
• Transmission

Starter

• Question: How does the energy of a sound change with distance? Which dolphins (small or large) are more likely to hear the sound? Explain.

• Answer: As distance from the sound source increases, the loudness/energy of the sound decreases. High-frequency sounds are absorbed faster than lower frequency sounds.

Sound Wave Behavior

• Sound waves behave in three ways: reflection, absorption, and transmission.

Group Work - Inquiry-Based Learning

• Search the meaning of sound transmission, absorption, and reflection.
• Consider:
  • What happens to your sound if you shout in empty room?
  • Why can you hear your brother when you talk in another room?
  • Why do singers record in rooms with soft walls?

Sound Reflection, Absorption, and Transmission

• Reflection: Occurs when a wave strikes an object and bounces off. An echo is reflected sound (sound bouncing off walls, surfaces etc)
• Hard, smooth surfaces reflect sound better than soft surfaces, which absorb most of the sound.
• Transmission: The propagation or speed of a sound wave through an object or medium.
• Absorption: The process of a wave losing energy when it interacts with a medium.

Check Your Understanding

• Compare and contrast absorption, reflection, and transmission of sound. (Diagram provided)

Activity - EdPuzzle

• Watch a video on sound reflection, absorption, and transmission on EdPuzzle, answering pop-up questions.

Day 2 - Lesson 2: Behavior of Waves - Sound Wave Interaction - Absorption and Frequency

• Standards:
  • MS-PS4-1: Use mathematical representations to describe a simple model for waves, including how amplitude relates to energy in a wave.
  • MS-PS4-2: Develop and use a model to describe how waves are reflected, absorbed, or transmitted through various materials.

Starter

• Describe what happens when a sound wave hits a wall. Explain.

Objectives

• Describe how sound is absorbed.
• Explain how sound absorption relates to the frequency of sound.
• Apply understanding of absorption to real-world examples (dolphin and whale communication at varying distances).

Absorption

• Why are movie theaters and recording studios designed with soft materials (carpets, foam, curtains)? For sound absorption

Absorption and Frequency

• Absorption can vary based on the frequency of the wave.
• High-frequency waves lose more energy to absorption than low-frequency waves.
• Higher frequency waves cause particles to move more often, leading to more energy loss (friction). Higher frequency waves lose energy faster.

Think-Pair-Share

• Whales and dolphins use sound underwater.
• Dolphins use high-frequency sound to locate objects.
• Whales use low-frequency sound to communicate over long distances.
• Higher frequency sounds are absorbed faster than lower frequency sounds.

What Happens When the Wave Hits the Wall?

• Full reflection occurs if the wave strikes a new medium (like a wall) and reflects into the original medium.
• Partial reflection and transmission if the wave hits a boundary between two mediums at a certain incident angle.

Checking Understanding

• This image shows a wave traveling from one medium to a less dense medium. What happens with the wave at the boundary? Answers:
• Part of the wave's energy is transmitted.
• Part of the wave is reflected back into the original medium.
• The transmitted part of the wave does not carry particles from one medium to the other.

Energy in Partially Reflected Waves

• When a wave is partially reflected, the original wave's energy is split between the reflected wave and the transmitted wave.
• Each new wave has less energy than the original wave.
• Amplitude depends on the medium.