DeBroglie wavelength, kE to (p) conversion?

AI Thread Summary
To calculate the deBroglie wavelength from kinetic energy, both the rest mass and velocity of the particle are necessary. Kinetic energy alone cannot be directly converted to momentum without additional information. In cases of non-relativistic speeds or speeds close to light, approximations may apply, but their effectiveness relies on the specific details available. Clarifying the known parameters of the particle could facilitate a more accurate approach. Understanding these relationships is crucial for accurate calculations in quantum mechanics.
Joel DB
Messages
4
Reaction score
0
I have a relatively simple question. I should know this, but...
I need to solve for the deBroglie wavelength when only the kinetic energy is known. Shouldn't I be able to convert kE to momentum (p), when the object does not have a known velocity or mass...?

Much thanks...
JD
 
Physics news on Phys.org
Joel DB said:
I have a relatively simple question. I should know this, but...
I need to solve for the deBroglie wavelength when only the kinetic energy is known. Shouldn't I be able to convert kE to momentum (p), when the object does not have a known velocity or mass...?

Much thanks...
JD
No. You need both the rest mass and the velocity to determine the kinetic energy of a relativistic particle. Alternatively, you can use the total energy and the rest mass to determine the momentum (essentially the same thing).

However, if you know that the particle is moving at non-relativistic speeds, or very close to the speed of light, then there are some approximations you can use. But again, the usefulness of these depends on what you know.

Perhaps it would be easier if you tell use precisely what you know.
 

Thread 'Errors and significant figures'

I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
View full post »
Thread 'A cylinder connected to a hanging mass'

Thread 'A cylinder connected to a hanging mass'

Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
View full post »

Similar threads

Wavelength = deBroglie Wavelength?
Replies
11
Views
2K
What Is the Kinetic Energy of a Proton at 1/4 the Speed of Light?
Replies
3
Views
2K
Colour depends on wavelength or frequency?
Replies
22
Views
1K
I DeBroglie wavelength & particle-wave duality
Replies
41
Views
5K
DeBroglie wavelength in infinite potential well
Replies
1
Views
6K
Calculate the kinetic energy of an electron with a wavelength of 1fm
Replies
1
Views
2K
I Energy-momentum formula and deBroglie wavelength
Replies
4
Views
2K
How to find the wavelength of a particle with mass?
Replies
1
Views
2K
Wavelength-stopping potential dependence
Replies
5
Views
2K
De Broglie wavelength of electron and proton
Replies
14
Views
3K

Hot Threads

Recent Insights

Back
Top