High School Apparent missing negative phase oscillation energy - where is it?

[harrylentil]

When an oscillator produces waves - let's say they are highly focused - that are damped by a second negative phase oscillator, where is the wave energy? The energy in each set of waves must still exist. Has it become hidden?

 

[davenn]

where is the wave energy? The energy in each set of waves must still exist. Has it become hidden?

You marked this with an A tag for post graduate, that infers you have done some serious study ... What do you think happens ?

You haven't stated what the phase of the negative phase oscillator is in relation to the other oscillator

 

[harrylentil]

You marked this with an A tag for post graduate, that infers you have done some serious study ... What do you think happens ?

You haven't stated what the phase of the negative phase oscillator is in relation to the other oscillator

Is that what those tags mean? I'm not even an undergraduate. I thought they were an indication of the level of the question (as though I would do better than a guess). I think the phase should be opposite that of the other oscillator to show the greatest effect.

 

[berkeman]

[Mentor Note -- Thread level changed A --> B]

 

[DaveE]

It sounds like maybe you are mixing the concepts of interference in waves (eg. "negative phase") and damping. Energy can be stored in the wave and/or it can be dissipated by damping, which is a term typically used to describe lossy processes. Interference can make the wave energy move around, or at least appear to, but it won't go away. If you really mean where does the energy go eventually, then it will be dissipated, usually as heat, in the damping mechanism.

While you can make the wave(s) amplitude go to zero via destructive interference, there will be other places where you get even more energy from constructive interference. It isn't lost by interference, except in a local sense.

If you describe your experiment in more detail, you might get a better answer.

 

[davenn]

.....). I think the phase should be opposite that of the other oscillator to show the greatest effect.

If the phase of the 2nd osc ( same frequency) is equal and opposite then the result will be a zero signal
as the 2 signals will cancel each other out

 

[harrylentil]

If the phase of the 2nd osc ( same frequency) is equal and opposite then the result will be a zero signal
as the 2 signals will cancel each other out

Yes, a zero signal. The two oscillators are expending energy, putting it into a volume where no, or little, energy is observed, because of destructive interference. How does this concealment work?

 

[hutchphd]

When an oscillator produces waves - let's say they are highly focused - that are damped by a second negative phase oscillator, where is the wave energy? The energy in each set of waves must still exist. Has it become hidden?

I don't know what you mean by highly focused. The short answer is that the energy will show up elsewhere: like squeezing a balloon.
Consider the ubiquitous two source interference pattern.

There are lines where the resultant displacement is null but there are lines where it is doubled. Energy is conserved.

If you are thinking of another example please be definite and specific

 

[harrylentil]

Sorry for being vague. I wrote 'highly focused' to give a picture where waves are projected into a constrained volume rather than outward in all directions. @hutchphd's image above wouldn't be that picture. I was thinking more of two beams directed at one another, oscillations exactly in opposite phase, and in the volume where they coexist there is apparently no energy but really there is hidden energy. I would like a physical picture of what is happening at the molecular level in that volume in this situation. Apologies for not being clearer earlier.

 

[hutchphd]

Waves move. Waves from two different sources will cancel over a very limited domain and there will be compensating regions where they add.
For your "two identical beams directed at each other" consider sources at each end of a taut string. The pattern in the middle will be an (oscillating) standing wave with nodes. At instants of time the string will be flat but the energy is all kinetic. A quarter period later the string will be stationary but sinusoidal an the energy is all potential.
I believe you need to carefully and more exactly describe your Gedanken circumstance. You will find that your thought experiment is not possible as you envision it.

 

[davenn]

How does this concealment work?

There IS NO concealment

but really there is hidden energy.

There IS NO hidden energy

 

[sophiecentaur]

a second negative phase oscillator,

WHERE is the relative phase negative? Answer: Not Everywhere because phase of a wave depends on both time and location. There must be locations where there is addition and not subtraction.
The only situation where you could have anti phase conditions everywhere would have to be when the source oscillators are in exactly the same place. Then they would be fighting each other and all the power would be wasted (lost) internally in the oscillators.