Welcome to blog help for PHY 122! Here's how it works.
For each homework question and lab report we will make a post, this will probably contain a few tips on what the problems are about and how to solve them. If you are stuck on something then instead of emailing us directly you should post a comment in reply to the relevant post. We will try to guide you through tough points and help you understand the problems and the concepts behind them.
Thursday, November 18, 2010
Chapter 27, problems 7 through 12
These problems pertain to material in the November 23 lecture.
Note that the assignment is due on Monday, November 29th.
5 comments:
Anonymous
said...
I am having trouble with problem #11 when entering the answer. I am getting that the speed of the electron is approximately 10^6 m/s, but no matter what I have tried webassign does not accept my answer. There is a "10" in front of the answer box and I'm not sure how that is affecting my answer.
this is why this blog is helpful, because if I hadn't read this, I wouldn't have known that putting a "6" would be the right answer. i would've kept inputting 1.0e6 and thought "why is this wrong?"
#8 is a Compton shift problem, and so the Compton shift equation is useful. Once you know the wavelength of the outgoing photon, and the fact that it is moving opposite the incoming one, you know both the kinetic energy transferred to the electron (difference of photon energies) and the momentum (difference of photon momenta, but keep track of the directions). If you need more detailed help, you have to tell me in more detail what you have done (maybe by email to me alone, to keep from spoiling the fun for everybody else in the class).
5 comments:
I am having trouble with problem #11 when entering the answer. I am getting that the speed of the electron is approximately 10^6 m/s, but no matter what I have tried webassign does not accept my answer. There is a "10" in front of the answer box and I'm not sure how that is affecting my answer.
It took me a while to figure it out as well, but WebAssign wants you to put in the exponent. So if you think the answer is 10^6, you should put in 6.
this is why this blog is helpful, because if I hadn't read this, I wouldn't have known that putting a "6" would be the right answer. i would've kept inputting 1.0e6 and thought "why is this wrong?"
-Vito
any hints for number 8? I have been using the compton shift equation, but after that, I get lost. Any suggestions?
Thanks
#8 is a Compton shift problem, and so the Compton shift equation is useful. Once you know the wavelength of the outgoing photon, and the fact that it is moving opposite the incoming one, you know both the kinetic energy transferred to the electron (difference of photon energies) and the momentum (difference of photon momenta, but keep track of the directions). If you need more detailed help, you have to tell me in more detail what you have done (maybe by email to me alone, to keep from spoiling the fun for everybody else in the class).
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