Standing Waves: Transverse?

[justadream]

Are all standing waves transverse waves?

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[echoyjeff222]

You can get standing waves from longitudinal waves too ... for example sound waves in air columns

 

[IslandStyle808]

There are transverse standing waves and longitudinal standing waves.

 

[justadream]

Oh okay that makes sense.

But are all sound waves longitudinal at least?

 

[IslandStyle808]

Oh okay that makes sense.

But are all sound waves longitudinal at least?

Nope. Light is transverse and sound is longitudinal.

It's best to think of the questions come at you like this:

Transverse vs. Longitudinal wave

Standing vs. Traveling wave

Look up some videos on youtube. It maybe best to see what you are learning, this will help you retain it.

 

[NextStepTutor_1]

Are all standing waves transverse waves?

These two characteristics (standing and transverse) have no relation to each other.
While it is true that most standing waves presented on practice problems refer to light waves (which happen to be transverse waves), describing a wave as "standing" does not mean it is also transverse.

A standing wave is a like a photo. It's a "still shot" of a moving wave.
For a moving wave - think about a person tying one end of a rope to a post and whipping the other end up and down. Waves travel the length of the rope for as long as the person is creating them and we see a haze of movement as waves move the rope up and down and collide with the post.

Light waves are transverse waves. (Remember that "light" ends with a "t" and "transverse" starts with a "t"). Transverse waves are characterized by oscillations that move perpendicular to the movement of the wave (or energy transfer). Think about the rope example above - the rope is moving up and down, but the waves are moving from side to side (person to post). That is an example of a transverse wave.
Sound waves are longitudinal waves. (Both words have the letter "u" in them). Longitudinal waves are characterized by oscillations that move parallel to the movement of the wave.


http://forums.studentdoctor.net/forums/next-step-mcat-tutor-office-hours.970/

 

[justadream]

Thanks for the responses everyone.

I have another question about standing waves in particular.

Standing waves are "standing" because the nodes/antinodes appear not to move. But let's say you look at an antinode (max displacement). Isn't the medium (let's say the standing wave is created by a string) still moving at the antinode? If so, why is it that it appears to stay maximally displaced in only one direction?

 

[NextStepTutor_1]

The antinode is the place of maximum displacement from the normal (on a standing wave picture that would be the x-axis), whereas the node is static - it has zero displacement from the x-axis.

In a standing wave, the antinode is experiencing the greatest net movement, or displacement, from +y to -y while the node is remaining on the x-axis.
In a picture of a standing wave the antinode at some +y can also move to -y as the wave moves, however at that particular instance in the picture the antinode is maximally displaced in "one direction" (+y). If you were shown a progression of pictures of this wave as it moved, the antinode would move from +y to -y.