Electric potential/potential energy

In summary, a proton and an electron both accelerate from rest through a potential difference of 190V, with the equation 1/2mv^2 = q(190V) being used for the electron. The electric potential due to a proton at the orbit of a hydrogen electron can be calculated using the equation V=kq/r, with the value of q being the charge of the proton (equal to that of an electron, but with opposite sign). The distance between the +14-V and +16-V equipotentials can be calculated using the equation V=ED, where E is the uniform electric field of 7500 N/C.
  • #1
triplezero24
16
0
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 +14-V and +16-V equipotentials?

I have no idea on this one.

Any help on any of these woulod be greatly appreciated. Thanks a ton in advance. :confused:

Eric
 
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  • #2
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: that's 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
MathStudent said:
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: that's 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

For part 1 I just don't see how to get the q for the proton. I just stumbled upon it for the other part.

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
triplezero24 said:
For part 1 I just don't see how to get the q for the proton. I just stumbled upon it for the other part.

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?
Realize that the charge of the proton is equal to that of an electron but has the opposite sign (that is its positive)... I believe I said this in an earlier post
triplezero24 said:
For part 3 you're saying that V = ED?
If you don't believe me remember that
[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 )
 
Last edited:
  • #5
MathStudent said:
Realize that the charge of the proton is equal to that of an electron but has the opposite sign (that is its positive)... I believe I said this in an earlier post

If you don't believe me remember that
[tex]\DeltaV = \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]\DeltaV = \vec{E}\int\vec{dl} [/tex]
And since [tex]\int\vec{dl} [/tex] is just equal to the distance traveled by the particle
[tex]\DeltaV = ED [/tex]


Sorry if it sounded like I didn't believe you. I just didn't fully understand you. :smile:
 
  • #6
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
It doesn't show, but it makes more sense now. Thanks a bunch.
 

1. What is electric potential?

Electric potential, also known as voltage, is a measure of the electric potential energy per unit charge at a point in an electric field. It determines the amount of work needed to move a unit charge from one point to another in an electric field.

2. How is electric potential calculated?

Electric potential is calculated using the formula V = W/q, where V is the potential, W is the work done, and q is the test charge. It can also be calculated by multiplying the electric field strength by the distance between two points.

3. What is the difference between electric potential and electric potential energy?

Electric potential is a measure of the potential energy per unit charge at a point in an electric field, while electric potential energy is the potential energy stored in an object due to its position in an electric field. Electric potential is a scalar quantity, while electric potential energy is a vector quantity.

4. How does distance affect electric potential?

As distance increases, electric potential decreases. This is because the electric field strength decreases with distance, so the work needed to move a unit charge also decreases. Therefore, the potential energy per unit charge decreases.

5. What is the relationship between electric potential and electric field?

The electric field is the negative gradient of the electric potential. This means that the direction of the electric field is in the direction of decreasing potential. In other words, the electric field points from areas of high potential to areas of low potential.

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