PLEASE HELP Question regarding uncertainty principle

AI Thread Summary
The discussion centers on the application of the uncertainty principle, specifically ΔEΔt > h/4π, to calculate the uncertainty in frequency associated with a photon emitted from an excited atom. The user correctly identifies Δt as 10^-10 s and attempts to calculate ΔE but mistakenly derives an unreasonably high velocity value. Participants clarify that the correct unit for frequency is s^-1, not ms^-1, and suggest comparing the calculated frequency uncertainty to typical values for visible light, which range from 10^14 to 10^15 Hz. This context helps the user assess whether their results are reasonable in relation to known frequencies. The conversation emphasizes the importance of unit consistency and proper interpretation of results in quantum mechanics.
xregina12
Messages
26
Reaction score
0
Analogous to the uncertainty relation ΔpΔx > h/4π, there is an uncertainty relation for the time and energy, ΔEΔt > h/4π that stems from the methods
usually used to measure the energy. The uncertainty in the time, Δt, can be interpreted as a lifetime. The excited state of an atom responsible for the emission of a photon has an average lifetime of 10^-10 s. What is the corresponding uncertainty in the frequency associated with the emitted photon?

What I understood based on the uncertainty principle:
ΔEΔt > h/4π and that Δt=10^-10 s here in this problem.
I can use this to calculate ΔE.
However, my next step is something I am not sure about. I set ΔE=hΔv and solved for v but then got 7.96x10^8 ms-1 which is so big and doesn't make sense to me.

Can anyone explain what I did wrong, why, and give me some guidance on what I should do to get the uncertainty in frequency?
 
Physics news on Phys.org
xregina12 said:
What I understood based on the uncertainty principle:
ΔEΔt > h/4π and that Δt=10^-10 s here in this problem.
I can use this to calculate ΔE.
However, my next step is something I am not sure about. I set ΔE=hΔv and solved for v but then got 7.96x10^8 ms-1 which is so big and doesn't make sense to me.

Can anyone explain what I did wrong, why, and give me some guidance on what I should do to get the uncertainty in frequency?
Do you mean for the units to be s-1 or ms-1?

Either way, consider that visible light has a frequency in the range of 1014-1015 Hz (or s-1). Compared to that, does your Δv value appear to be large or small?
 
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...
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...
Back
Top