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Electric potential/potential energy 
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#1
Jan1905, 07:39 PM

P: 16

Ok I have a couple questions here.
1. Calculate the speed of a proton and an electron after each particle accelerates from rest through a potential difference of 190V. I think I got the part of the electron because I randomly came across the energy value of an electron. The equation I'm using is 1/2mv^2 = q(190V) 2. A hydrogen electron orbits its proton in a circular orbit of radius 0.529X10^10 meters. What is the electric potential due to the proton at the electron's orbit? V=kq/r right? But where do I find the q?? 3. A uniform electric field E=7500 N/C points in the negative x direction. What is the distance between the +14V and +16V equipotentials? I have no idea on this one. Any help on any of these woulod be greatly appreciated. Thanks a ton in advance. Eric 


#2
Jan1905, 07:47 PM

P: 281

part 1 looks right... you can do the same for a proton just don't forget to change the values of m and q.
part 2: thats the right equ'n... the q is referring to the source charge which in this case I believe to be the charge of the proton (should be in your book / same as e but opposite sign) part 3: the equ'n for potential for a uniform electrical field is ED 


#3
Jan1905, 08:04 PM

P: 16

FOr part 2 the q value is definitely not in my book. I looked in all the appendices and everything. For part 3 you're saying that V = ED? 


#4
Jan1905, 08:19 PM

P: 281

Electric potential/potential energy
[tex]\Delta V = \int\vec{E}\cdot\vec{dl}[/tex] since [itex]\vec{E} [/itex] is constant , this can be taken out of the integral and this becomes [tex]\Delta V = \vec{E}\int\vec{dl} [/tex] And since [tex]\int\vec{dl} [/tex] is just equal to the distance traveled by the particle [tex]\Delta V = ED [/tex] (where the above integrals are definite line integrals whose lower limit is the starting point and upper limit is the end point of the path ) 


#5
Jan1905, 08:20 PM

P: 16

Sorry if it sounded like I didn't believe you. I just didn't fully understand you. 


#6
Jan1905, 08:21 PM

P: 281

Thats fine.... you should question everything rather than take it at face value, its part of the learning process :)
PS: It should show a "Delta v" before each equals sign,,, is it showing up for you? 


#7
Jan1905, 08:34 PM

P: 16

It doesn't show, but it makes more sense now. Thanks a bunch.



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