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### 1.37

Posted: Sun Oct 15, 2017 2:38 pm
Hi!
Can someone please explain 1.37 from the textbook HW problems. I know I need to use the De Broglie equation, but how do I find the mass of a proton/neutron? Is it just a value I should have memorized, or would it be given?

1.37) Protons and neutrons have nearly the same mass. How different are their wavelengths? Calculate the the wavelength of each particle when traveling at 2.75 x 10^5 m/s in a particle accelerator and report the difference as a percentage of the wavelength of a neutron.

Thanks so much!

### Re: 1.37  [ENDORSED]

Posted: Sun Oct 15, 2017 2:50 pm
I think the mass would be given since in Example 1.6, Self-Test 1.6A, the question mentions that the mass of an electron can be found inside the back cover of the book. There, you can also find the mass of a proton.

### Re: 1.37

Posted: Sun Oct 15, 2017 4:02 pm
You can also find the masses of both particles on the class website! It's in a worksheet named constants and equations, just in case you wanna have a separate page to look at so you're not constantly flipping the pages of your book :)

### Re: 1.37

Posted: Wed Oct 18, 2017 12:22 am
On #37 and #41, you need to know the mass of a proton and neutron, which are not given in the question. Is this something we should memorize for tests? Are there any other masses that we should memorize the value of?

### Re: 1.37

Posted: Wed Oct 18, 2017 2:22 pm
Hi
I think their masses would be given on a separate sheet attached to the exam paper.

### Re: 1.37

Posted: Fri Oct 20, 2017 10:18 am
I can confirm that a constants and equations sheet will be provided! Going back to the original question though, I was confused by the last part: "report the difference as a percentage of the wavelength of a neutron". Are we supposed to just calculate both wavelengths, find the difference then divide by the wavelength of a neutron? Wouldn't we just get 0% since the wavelengths end up being nearly identical?