Measuring energy of photon to within some accuracy

AI Thread Summary
To measure the energy of a photon with an accuracy of 10^(-15) Joules, the discussion highlights the relevance of the Heisenberg uncertainty principle, which relates energy and time through Planck's constant. The initial attempts to solve the problem involved considering the relationship between energy, frequency, and wattage, but these approaches were deemed inadequate. The realization that the uncertainty principle is key to deriving the necessary time measurement was a breakthrough for the participant. This emphasizes the importance of understanding fundamental physics concepts when tackling such problems. Overall, the discussion underscores the connection between energy measurement accuracy and quantum mechanics principles.
quasar_4
Messages
273
Reaction score
0

Homework Statement



Estimate the minimum length of time needed to measure the energy of a photon to an accuracy of 10^(-15) Joules.

Homework Equations



E = hv, where v is the frequency of the photon and h is Planck's constant in J*s

Watts = Joules/second

The Attempt at a Solution



I can think of two ways to get the units to work out right, but I'm fairly certain they're not right. One would be to ignore the specific frequency of the photon, assuming that E is proportional to Planck's constant in J*s, and dividing to obtain an answer in seconds. But that seems unreasonable to me since the wavelength of the photon should plausibly matter.

The only other thing that comes to mind straight away is to somehow utilize the definition of watts, to determine how long it would take to get some wattage, but I don't feel that this is right, either.

What am I missing? I'm sure this is a simple, 30 second problem, I'm just having a mind block... :rolleyes:
 
Physics news on Phys.org
Are you certain you need to use E = hv?
I think this is a problem dealing with the Heisenberg uncertainty princple, relating energy with time and Planck's constant. Maybe you should read up on it?
 
aha, that's perfect! I can't believe I didn't even think of it. I knew I was missing something easy. It's easy to derive the uncertainty principle with commutators, too, in case one has forgotten that as well. Thanks!

(See what 4 months of break from school does to the mind?? )
 

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

Photon Arrival Rate, Chapter 1.5 from Computer Graphics by Folly
Replies
15
Views
2K
How many Photons per second are entering the pupil?
Replies
6
Views
5K
Solving Photon Energy with Equations: Am I Right?
Replies
48
Views
3K
Calculating the Planck Length
Replies
3
Views
216
Photon energy and calculating frequency
Replies
2
Views
2K
Finding the momentum of a photon
Replies
11
Views
3K
How can I calculate the number of photons with this data?
Replies
7
Views
2K
Photons per second from lightbulb
Replies
3
Views
2K
How Much Mass Converts to Energy in a Nuclear Plant Over a Month?
Replies
2
Views
2K
What are the Units for the momentum of a Photon?
Replies
6
Views
8K

Hot Threads

Recent Insights

Back
Top