Electrical potential difference given velocity

In summary, the problem involves an electron moving parallel to the x-axis with an initial speed of 3.7x10^6m/s at the origin. The speed is reduced to 1.4x10^5m/s at the point x=2.0 cm. The potential difference between the origin and this point is being asked for, as well as which point is at the higher potential. The equations Uq = 0.5mv^2 and U_{AB}\cdot q=W_{AB} may be useful in solving this problem. The electron has a negative charge, so it might be necessary to ignore the negative sign in order to use the equations directly. However, if a negative potential difference is obtained,
  • #1
famallama
9
0

Homework Statement


An electron moving parallel to the x-axis has in initial speed of 3.7x10^6m/s at the origin. Its speed is reduced to 1.4x10^5m/s at the point x=2.0 cm. What is the potential difference between the origin and this point? Which point is at the higher potential?


Homework Equations


I am not sure what equations are useful with this equation.


The Attempt at a Solution


I have not been able to attempt this problem, I have no idea how i would go about starting it
 
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  • #2
I'm a little unsure, but perhaps you could use the fact that Uq = 0,5 m v^2, at least for the first questions. I don't quite know what is meant by the second question, but electrons are negative. So try that.
 
  • #3
Anden, examine the equation you posted carefully, what happens if the charge is negative? Does that make sense physically?

What is the electron's kinetic energy at the origin?
What is its kinetic energy at point x?

What does this say about the work done on the electron?

What is the relationship between the work done on a mass moving it from point A to point B, and the potential difference between those two points?
 
  • #4
Is it really that simple? there is nothing special about it being in the electrical potential section?

If its Uq then is q the charge of the electron? Or do i simply have to find the kinetic energy?
 
  • #5
Ups, yes of course you're right, the electron has negative charge. But I think if you forget that and count the electrons charge as positive, you can use the equation to get directly to the potential difference.

EDIT: A thought: If you get a negative potential difference, doesn't that describe what's going on here? I mean, you get a general idea of the direction of the acceleration of the electron.
 
  • #6
Anden said:
Ups, yes of course you're right, the electron has negative charge. But I think if you forget that and count the electrons charge as positive, you can use the equation to get directly to the potential difference.

EDIT: A thought: If you get a negative potential difference, doesn't that describe what's going on here? I mean, you get a general idea of the direction of the acceleration of the electron.

Oh, so since it comes out nonsensical (A square equaling a negative) we just ignore the problem? :P

I haven't brushed up on the subject in a while, but I'm pretty sure that [tex]U_{AB}\cdot q=W_{AB}[/tex]
 
  • #7
What do you mean by a square equaling a negative? And why is it so non-sensical? ;) And what happens with a negative charge in Uq = W?
 

1. What is electrical potential difference?

Electrical potential difference, also known as voltage, is a measure of the difference in electric potential energy between two points in an electric field. It is measured in volts (V) and represents the amount of energy needed to move a unit of electric charge from one point to another.

2. How is electrical potential difference related to velocity?

Electrical potential difference is not directly related to velocity. However, the movement of charged particles, such as electrons, through an electric field can result in a change in velocity and, therefore, a change in electrical potential difference.

3. What factors affect electrical potential difference?

Electrical potential difference is affected by factors such as the distance between two points in an electric field, the type of material the charges are moving through, and the amount of charge present. Additionally, the presence of external sources, like batteries or generators, can also affect electrical potential difference.

4. How is electrical potential difference measured?

Electrical potential difference is measured using a voltmeter, which is a device that measures the difference in electric potential energy between two points. The voltmeter is connected in parallel to the two points in an electric circuit and displays the measured potential difference in volts.

5. What is the effect of changing electrical potential difference on a circuit?

Changing electrical potential difference can have various effects on a circuit, depending on the specific circumstances. For example, increasing the potential difference in a circuit with a constant resistance will result in an increase in current. However, if the resistance is also changed, the effect on the current may be different. Generally, a change in potential difference can impact the flow of current and the overall functioning of a circuit.

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