# Electric Potential and Superposition of Electric Potential

• spark2flame
In summary, the electric potential energy of the configuration is equal to the change in electric potential energy.

#### spark2flame

1. Three charges are placed at the corners of a rectangle (one charge of -3.3e-6 C is placed on the bottom left hand corner, one charge of 2.7e-6 C on the upper right hand corner, and one charge of -6.6e-6 C on the upper left hand corner.) of length x = 0.65 m and height y = 0.43 m. How much work must be done to move the three charges infinitely far from one another?

2. U = (k*q*qo)/r

3. I tried using the superposition of the electric potential energy, but this did not yield the right answer. I don't know how to find the energy to push the charges to infinity!

Find the electric potential energy of the configuration by considering all the charge pairs.

Yes, I tried that using U = (k*q*qo)/r while considering the three different charges (which means that there would be three different U values). Would you simply use this formula for the three different charges and add the values? Does this account for the fact that you are trying to push the charges to infinity?

spark2flame said:
Would you simply use this formula for the three different charges and add the values?
Use the formula for three different charge pairs.
Does this account for the fact that you are trying to push the charges to infinity?
You'll compare the electric PE before and after you've moved the charges to infinity.

Okay that makes sense about the charge pairs. So would you simply add the U values found before and after pushing the charges to infinity? Or would you do U(initial) - U(final), or would you do U(final) - U(initial)?

The amount of work required to move the charges will equal the change in PE.

Ohhh okay so its U(initial)-U(final)?

But how would you calculate the U(final) for each charge pair, which would be U = (k*q*qo)/r, if the r approaches infinity and makes U = 0? Wouldnt that make the change in PE the same thing as U(initial)?

spark2flame said:
Ohhh okay so its U(initial)-U(final)?
Change is always final - initial.
But how would you calculate the U(final) for each charge pair, which would be U = (k*q*qo)/r, if the r approaches infinity and makes U = 0?
Exactly.

hahaha FINALLY i got the right answer. thanks SO much!

## 1. What is electric potential?

Electric potential is a physical quantity that measures the amount of work needed to move a unit charge from one point to another in an electric field. It is also known as voltage and is measured in volts (V).

## 2. How is electric potential calculated?

The electric potential at a point in an electric field is calculated by dividing the work done in moving a unit charge from infinity to that point by the magnitude of the charge. This can also be expressed as the product of the electric field strength and the distance from the point to the source of the field.

## 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 specific point in an electric field. It is a scalar quantity, while electric potential energy is a measure of the potential energy of a charge in an electric field. It is a vector quantity that takes into account both the magnitude and direction of the electric field.

## 4. What is superposition of electric potential?

Superposition of electric potential is the principle that states the total electric potential at a point due to multiple sources is equal to the algebraic sum of the individual potentials at that point. This means that electric potentials from different sources can be added together to determine the total potential at any given point.

## 5. How does distance affect electric potential?

According to the inverse-square law, the electric potential decreases as the distance from the source of the field increases. This means that the potential energy of a charge decreases as it moves away from the source of the electric field.