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Middle school physics - NGSS

Course: Middle school physics - NGSS>Unit 4

Lesson 2: Mechanical waves and light

Mechanical waves and light

Mechanical waves and light waves are two different wave types that can both be represented with a model. Learn about a key difference between these two waves and which wave properties can be represented as the brightness and color of light. Created by Sal Khan.

Want to join the conversation?

• what is the light with the highest wavelength called
• red has the longest wavelength, at around 700 nanometers.
• What types of energy in thermal energy.
• Thermal Energy is the energy that heat (or the lack of) produces. If you use a thermal imaging camera, you'll see that a stove top burner perhaps, is far brighter then the inside of a refrigerator, as the burner is HOT and the fridge is COLD.
• What is the trough
• The lowest point of the wave.
• Do waves have mass?
• Yes, waves have mass. However, the amount of mass they have is very small and difficult to measure. Waves are made up of energy, and according to Einstein's famous equation E=mc², energy and mass are interchangeable. So while waves do have mass, it is not significant enough to make a noticeable impact on their behavior or the world around them.
• Look at Khanmigo's rap:

Yo, we're talking 'bout waves, they're on the scene,
Traveling disturbances, if you know what I mean.
Up and down on a rope, they slide,
In water, they got nothing to hide.

Sound waves in the air, they bounce,
High and low pressure, ounce by ounce.
Creating sounds that we hear,
Traveling compressions, loud and clear.

Amplitude, wavelength, frequency too,
Important parts of the wave crew.
Mechanical waves need a medium to flow,
Like air, water, or a rope to throw.

Light waves, they're a different breed,
No medium needed, they take the lead.
Different frequencies, a colorful sight,
Electromagnetic waves, oh so bright!
• Wait, so... Radio is light? and it turns into sound?
• Visible light is a small part of the electromagnetic spectrum. Radio waves are light except that we can't see it or hear it. Our radio converts the radio wave into sound.
(1 vote)
• ok sal khan you may know now but for the kids who may not under stand. Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes. oh and i forgot to mention this was at
• the outer ear captures the sound waves which go into the ear canal. the eardrum is then hit which moves the hammer, anvil and stirrup. the stirrup hits the cochlea, sloshing the liquid inside. the liquid moves hairs in the cochlea which send a chemical-electrical message to your brain. then the brain interprets the messages and lets you react to the sound. all of this is done way faster than you can read it.