Electric potential, voltage
- electric potential energy
- electric potential (also known as voltage)
Work and potential energy
Electrical potential energy resembles gravitational potential energy
Doing work in an electric field
The amount of work done is force times distance, . The distance moved is . What is the force? This is a bit trickier, because the force changes all along the path. The closer we get to , the greater the force of repulsion. The closer we get, the harder we have to push to make move. Set up some variables so we can talk about what's going on here.
- is the distance from to the current position of .
- is a tiny change in distance. is so tiny we can consider the electric force constant over this distance.
Electric potential energy
Question: How has 's potential energy changed?
Electric potential difference
Electric potential difference has units of joules/coulomb.
- Subtracting the starting potential from the ending potential to get the potential difference, and
- Multiplying potential difference by the actual charge of the introduced object.
Electric potential near a point charge
- Electric potential energy is a property of a charged object, by virtue of its location in an electric field. Electric potential energy exists if there is a charged object at the location.
- Electric potential difference, also known as voltage, is the external work needed to bring a charge from one location to another location in an electric field. Electric potential difference is the change of potential energy experienced by a test charge that has a value of .
- Electric potential exists at one location as a property of space. A location has electric potential even if there is no charged particle there.
- Absolute voltage at a location is something we can talk about as long as everyone agrees that zero volts is way out at infinity. The concept of absolute voltage is sort of a verbal sleight-of-hand. It is always safe to stick with the definition: voltage is a potential difference.