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### Course: Middle school physics>Unit 4

Lesson 2: Mechanical waves and light

# Mechanical waves and light

Review your understanding of mechanical waves and light in this free article aligned to NGSS standards.

## Key points:

• Some waves can only travel through a material, or medium, such as air or water. These are called mechanical waves.
• Sound waves, water waves, and seismic waves are all types of mechanical waves.
• Other waves, called electromagnetic waves can travel through a medium or through a vacuum where there is no matter, such as outer space.
• Light is a form of electromagnetic wave.
• The amplitude and frequency of both mechanical and electromagnetic waves affect how we experience them.
• A light wave’s amplitude determines how intense, or bright, it is. Its frequency determines the light wave’s color.
• A sound wave’s amplitude determines how loud it is. Its frequency determines the sound wave’s pitch.

## Want to join the conversation?

• what causes the color to move?
• The frequency of waves. Like how many waves a second. For example, low frequency would affect the color (blue, red, yellow). Like this wave: ~~~~. A more frequent wave is this: /\/\/\/\/\/\/\. That will affect the color a bit different.
• How are all of these comments ridiculous? Don't get me wrong, they're hilarious, but this is such a fascinating topic, and deserves more respect.
• cuz some people are just bored.
• you should be able to see a light wave because it waves are you :)
• You can't because the visible light we see has wavelengths of 400-700 nanometers, which our eyes can not see.
• what is a mechanical wave
• In physics, a mechanical wave is a wave that is an oscillation of matter, and therefore transferes energy through a medium.While waves can move over long distances, the movement of the medium of transmission—the material—is limited. Therefore, the oscillating material does not move far from its initial equilibrium position. Mechanical waves can be produced only in media which possess elasticity and inertia. There are three types of mechanical waves: transverse waves, longitudinal waves, and surface waves. Some of the most common examples of mechanical waves are water waves, sound waves, and seismic waves.

Like all waves, mechanical waves transport energy. This energy propagates in the same direction as the wave. A wave requires an initial energy input; once this initial energy is added, the wave travels through the medium until all its energy is transferred. In contrast, electromagnetic waves require no medium, but can still travel through one.
• why colors
• idk maybe because colors are a relaxing thing to the human brain and when the colors brightness or exposure increases it is not a very relaxing thing to the human brain :)
• How does frequency work in real life?
• frequency actually doesnt come in waves as shown in the videos but actually is shaped more like curve lines expanding outwards exponentially and nets when stacked. the light also fades and becomes dimmer the more the light expands.( the longer the distance between the light source and the object, the more the light waves expands)
(1 vote)
• Why is air consider a matter?
• Because air has particles in it.