Tbr wave questions

[yjj8817]

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For this problem, answer key says that frequency is not affected. Why is it that only wavelength is affected?

For this problem, does constructive interference create both drop and rise in the water level?

Thank you!

 

[kfcman289]

ocean water will be denser with more pressure, and I believe that a decrease in wavelength is what decreases the speed, not frequency.

 

[Thoroughbred_Med]

FREQUENCY OF A WAVE NEVER CHANGES!

 

[yjj8817]

FREQUENCY OF A WAVE NEVER CHANGES!

Thanks, but why?

 

[Cawolf]

Frequency is a property of the source and will not be changed by the medium (due to conservation of energy).

Therefore if two waves of equal energy and frequency move through mediums with different velocities, the wavelength will vary.

 

[Thoroughbred_Med]

Frequency is a property of the source and will not be changed by the medium (due to conservation of energy).

Therefore if two waves of equal energy and frequency move through mediums with different velocities, the wavelength will vary.

Ok. So that leads me to a question... I know that the color 'violet' has a wavelength of 400 nm... but if violet light shines from air into a more dense medium (oil), and its wavelength decreases, is the color 'violet' not seen in the oil anymore bc it's not at its characteristic wavelength of 400nm?

 

[Cawolf]

@Thoroughbred_Med

The color is dependent on the energy of the wave - which is proportional to the frequency.

The color violet only has a wavelength of around 400 nm in a vacuum.

 

[Thoroughbred_Med]

@Thoroughbred_Med

The color is dependent on the energy of the wave - which is proportional to the frequency.

The color violet only has a wavelength of around 400 nm in a vacuum.

Well, frequency always stays the same. So can we assume that the color violet would stay violet when crossing from n= 1.0 to n= 1.5 medium?

 

[Cawolf]

Yes, exactly.

 

[yjj8817]

Yes, exactly.

So I know that light's wavelength changes with medium. Does this happen with any waves?

 

[Cawolf]

Yes. The velocity of a longitudinal wave is inversely proportional to the root of the density of the medium.

Basically, the velocity decreases as the medium gets denser - but the frequency stays the same. We know f = v/lamda is constant. So as the wave goes through a denser medium, the velocity will decrease and the wavelength will also decrease proportionally.