# Relationship between electric potential and velocity

### Electric Potential related to velocity | Physics Forums

We want to find the potential at a point because if we have it we can compute the energy any particle of charge Q will have at that point by just multiplying Q by. Homework Help: Electric Potential related to velocity. Dec 16 What is the relationship between kinetic energy and speed? What, then, is the. What is the speed of the electron when it strikes the screen? Solution: is the product of the charge and the difference in electric potential between these points .

The above statements and the formula are valid regardless of the path through which the charge is moved. A particular interest is the potential of a point-like charge Q. It can be found by simply performing the integration through a simple path such as a straight line from a point A whose distance from Q is r to infinity.

Path is chosen along a radial line so that becomes simply Edr. Note that potential function is a scalar quantity as oppose to electric field being a vector quantity.

Now, we can define the electric potential energy of a system of charges or charge distributions. Suppose we compute the work done against electric forces in moving a charge q from infinity to a point a distance r from the charge Q.

The work is given by: Note that if q is negative, its sigh should be used in the equation! Therefore, a system consisting of a negative and a positive point-like charge has a negative potential energy.

### Relationship between charge and electric potential - Electrical Engineering Stack Exchange

A negative potential energy means that work must be done against the electric field in moving the charges apart! Now consider a more general case, which deals with the potential in the neighborhood of a number of charges as depicted in the picture below: Let r1,r2,r3 be the distances of the charges to a field point A, and r12, r13, r23 represent the distance between the charges.

The electric potential at point A is: If we bring a charge Q from infinity and place it at point A the work done would be: The total Electric Potential Energy of this system of charges namely, the work needed to bring them to their current positions can be calculated as follows: Add all of the work needed to compute the total work. The result would be: Finding Electric Field from Electric Potential: The component of E in any direction is the negative of the rate of change of the potential with distance in that direction: Electric field is the gradient of electric potential.

Electric field lines are always perpendicular to the equipotential surfaces. These are imaginary surfaces surrounding a charge distribution.

**Relationships between current and driift velocity**

The distance between them is 5 cm. The ball with the smaller charge has a mass of 30 g; the other ball has a mass of 40 g. Initially they are at rest, but when the string is cut they move apart. When they are a long way away from each other, how fast are they going?

## Homework Help: Electric Potential related to velocity

Let's start by looking at energy. No external forces act on this system of two charges, so the energy must be conserved. To start with all the energy is potential energy; this will be converted into kinetic energy.

Energy at the start: Energy is conserved, so the kinetic energy at the end is equal to the potential energy at the start: The masses are known, but the two velocities are not. To solve for the velocities, we need another relationship between them. Because no external forces act on the system, momentum will also be conserved. Before the string is cut, the momentum is zero, so the momentum has to be zero all the way along.

The momentum of one ball must be equal and opposite to the momentum of the other, so: Plugging this into the energy equation gives: Electric potential Electric potential is more commonly known as voltage.

The potential at a point a distance r from a charge Q is given by: If there is a pressure difference between two ends of a pipe filled with fluid, the fluid will flow from the high pressure end towards the lower pressure end.

Charges respond to differences in potential in a similar way. Electric potential is a measure of the potential energy per unit charge. If you know the potential at a point, and you then place a charge at that point, the potential energy associated with that charge in that potential is simply the charge multiplied by the potential. Electric potential, like potential energy, is a scalar, not a vector. These often appear on field line diagrams.

Equipotential lines are always perpendicular to field lines, and therefore perpendicular to the force experienced by a charge in the field.