Relativistic Calculations for De-Broglie Wavelength

In summary, there is a question about the energy at which a non-relativistic calculation of the De Broglie wavelength of an electron will have a 5% error. There are two logical solutions, but with different values. The second approach, which considers momentum instead of energy, is the correct one for relativistic speeds. The first approach, which replaces momentum with kinetic energy, is not valid for relativistic speeds.
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Homework Statement


At what energy will a non-relativistic calculation of the De Broglie wavelength of an electron be in error by 5%? What is this energy for a proton? Comment on your results.

Homework Equations


I have two (seemed to be) logical answers for this question, but with different values

how to resolve this, there must be at least one wrong answer

i need a resolution [/B]

The Attempt at a Solution


Solution 1
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Solution 2
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  • #2
The second approach has the right relativistic de-Broglie wavelength. It depends on the momentum, not on "the energy above the rest energy plugged into the nonrelativistic expression".
 
  • #3
As far as i understand, there is nothing in the first approach states that the De-Broglie wavelength depend in anything but the momentum
in the first approach i replaced the momentum by the kinetic energy, and this is a valid replacement

please explain your point
 
  • #4
You replaced momentum by the kinetic energy in nonrelativistic mechanics. It won't give the right result for relativistic speeds.
 
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Related to Relativistic Calculations for De-Broglie Wavelength

1. What is the De-Broglie wavelength?

The De-Broglie wavelength is a concept in quantum mechanics that describes the wavelength of a particle, such as an electron, as it behaves like a wave. It is given by the equation λ=h/mv, where h is Planck's constant, m is the mass of the particle, and v is its velocity.

2. What is the importance of relativistic calculations for De-Broglie wavelength?

Relativistic calculations take into account the effects of special relativity, such as time dilation and length contraction, on the De-Broglie wavelength. This is important for accurately predicting the behavior of particles moving at high speeds, such as electrons in particle accelerators.

3. How do relativistic calculations affect the De-Broglie wavelength of a particle?

Relativistic calculations show that as a particle's velocity increases, its De-Broglie wavelength decreases. This is due to the effects of time dilation, which causes the particle to experience time at a slower rate, and thus decreases the frequency of its wave-like behavior.

4. Can the De-Broglie wavelength be measured?

Yes, the De-Broglie wavelength can be measured using various experimental techniques, such as electron diffraction or neutron interferometry. These measurements have confirmed the predictions of relativistic calculations and have provided evidence for the wave-particle duality of matter.

5. How are De-Broglie wavelengths used in practical applications?

De-Broglie wavelengths have practical applications in fields such as electron microscopy, where the wavelength of an electron beam is used to image objects at a nanoscale level. They are also used in particle accelerators, where the precise measurement and manipulation of particle wavelengths is crucial for producing high-energy collisions.

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