Superposition, amplitudes and superposed waves.

In summary: So, to answer your question, the intensity for the superposed wave should be 25 unit^2.In summary, the conversation discusses a problem involving calculating the intensity of two waves that are either mutually coherent or incoherent. The solution for mutually coherent waves involves adding the squared amplitudes, while for incoherent waves, a phase difference must be taken into account. The final answer for the intensity of the superposed wave is 25 unit^2.
  • #1
isabelle87
4
0
First off:
Sorry. I'm a Norwegian girl, so my English may not be of very good quality.
Now that's said...

I have this problem to solve.
Only thing is - I don't have a clue how!
I'm no good at physics, but unfortunately I have to have this class.

Anyway.
My problem is this:

Task 1a)
Two harmonic waves are mutually coherent.
One wave has an intensity of 4 unit^2,
the other wave has the intensity of 9 unit ^2,
their superposition wave will have an amplitude of

Task 1b)
Two waves are mutually incoherent.
One wave has an amplitude of 3 unit,
the other wave has an amplitude of 4 unit.
The intensity for the superposed wave should be?

How do I calculate this?
What formula am I suppose to use?
And if you only wan't to give me the formula,
can you please explain what the different letters, symbols and stuff means (so that I can solve it myself, if you don't want to give me the direct answer?)
 
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  • #2
hmmm

1a)the intensity is propotional to the amplitude squared. if they're mutually coherent you add the amplitudes and square the resultant (ans= 25 unit^2 i think)

1b)if mutually incoherent, there's a phase difference. so for all you know, a peak of one wave could coincide with a trough of the other. The resultant amplitude is anywhere from 1 to 7 (ie. intensity=1 to 49)
 
  • #3
Thank you for your reply, but did you perhaps overlook that it said "9 unit^2"?

Anyway.
If I now do this your way it'll be like this rigth?
9^2 + 4^2 = 97
And you believed I should square the result so that the final answer would be 97^2.

I don't know if this is right,
but either way I'm really thankful for your advice/opinion.
It's certainly worth a try!

:D
 
  • #4
The second answer you gave me seems to be wrong,
I found out to crack it on my own.
Or... At least i think I did ;)

Because the waves are incoherant I have to use the formula:
I = I1 + I2
= 3^2 + 4^2
= 25

The intensity for the superposed wave should be 25.
 
  • #5
^^ Not sure if that's correct TBH.

I(total) is infact I1+I2+(A1*A2)cos(X)

where X is the phase difference between the two waves and A is the amplitude. Incoherent waves, by definition, have a difference in phase.
 

1. What is superposition in relation to waves?

Superposition is the principle that states when two or more waves meet, the resulting wave is the sum of the individual waves. In other words, the amplitudes of the waves are added together at each point in space and time.

2. What are amplitudes in relation to waves?

Amplitudes are the maximum displacement of a wave from its resting position. In other words, it is the height of the wave from the midpoint to either the crest or trough.

3. How are superposed waves different from normal waves?

Superposed waves are the result of two or more waves overlapping and interacting with each other, while normal waves are individual waves that do not interact with each other. Superposed waves can exhibit interference patterns, while normal waves do not.

4. Can superposition occur with any type of wave?

Yes, superposition can occur with any type of wave, including sound, light, and electronic waves. This principle applies to all types of waves, as long as their properties (such as amplitude and frequency) can be added together.

5. How is superposition used in practical applications?

Superposition has many practical applications in various fields such as acoustics, optics, and electronics. For example, it is used in noise-cancelling headphones to cancel out unwanted sound waves, and in quantum computing to manipulate multiple superposed states simultaneously.

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