# Relationship between electric potential and voltage

### Electric potential | physics | az-links.info

Now we want to explore the relationship between voltage and electric field. We will start with the general case. Electric potential, the amount of work needed to move a unit charge from a q located between two plates, A and B, of an electric field E. The electric force F field between positive and negative electric potentials (voltages), much like the . Voltage, electric potential difference, electric pressure or electric tension is the difference in electric potential between two points. The difference in electric potential between two points (i.e., voltage) in a .. In relation to "flow", the larger the "pressure difference" between two points (potential difference or water pressure.

This work would increase the potential energy of the charge and thus increase its electric potential. As the positive test charge moves through the external circuit from the positive terminal to the negative terminal, it decreases its electric potential energy and thus is at low potential by the time it returns to the negative terminal.

If a 12 volt battery is used in the circuit, then every coulomb of charge is gaining 12 joules of potential energy as it moves through the battery. And similarly, every coulomb of charge loses 12 joules of electric potential energy as it passes through the external circuit. The loss of this electric potential energy in the external circuit results in a gain in light energy, thermal energy and other forms of non-electrical energy.

With a clear understanding of electric potential difference, the role of an electrochemical cell or collection of cells i.

The cells simply supply the energy to do work upon the charge to move it from the negative terminal to the positive terminal.

By providing energy to the charge, the cell is capable of maintaining an electric potential difference across the two ends of the external circuit.

Once the charge has reached the high potential terminal, it will naturally flow through the wires to the low potential terminal.

### Electric Potential Difference

The movement of charge through an electric circuit is analogous to the movement of water at a water park or the movement of roller coaster cars at an amusement park. In each analogy, work must be done on the water or the roller coaster cars to move it from a location of low gravitational potential to a location of high gravitational potential.

Once the water or the roller coaster cars reach high gravitational potential, they naturally move downward back to the low potential location. For a water ride or a roller coaster ride, the task of lifting the water or coaster cars to high potential requires energy.

The energy is supplied by a motor-driven water pump or a motor-driven chain. In a battery-powered electric circuit, the cells serve the role of the charge pump to supply energy to the charge to lift it from the low potential position through the cell to the high potential position.

It is often convenient to speak of an electric circuit such as the simple circuit discussed here as having two parts - an internal circuit and an external circuit. The internal circuit is the part of the circuit where energy is being supplied to the charge. For the simple battery-powered circuit that we have been referring to, the portion of the circuit containing the electrochemical cells is the internal circuit.

The external circuit is the part of the circuit where charge is moving outside the cells through the wires on its path from the high potential terminal to the low potential terminal. The movement of charge through the internal circuit requires energy since it is an uphill movement in a direction that is against the electric field. The movement of charge through the external circuit is natural since it is a movement in the direction of the electric field.

When at the positive terminal of an electrochemical cell, a positive test charge is at a high electric pressure in the same manner that water at a water park is at a high water pressure after being pumped to the top of a water slide.

Being under high electric pressure, a positive test charge spontaneously and naturally moves through the external circuit to the low pressure, low potential location.

### Electric potential, voltage (article) | Khan Academy

As a positive test charge moves through the external circuit, it encounters a variety of types of circuit elements.

Each circuit element serves as an energy-transforming device.

Light bulbs, motors, and heating elements such as in toasters and hair dryers are examples of energy-transforming devices. In each of these devices, the electrical potential energy of the charge is transformed into other useful and non-useful forms. For instance, in a light bulb, the electric potential energy of the charge is transformed into light energy a useful form and thermal energy a non-useful form.

The moving charge is doing work upon the light bulb to produce two different forms of energy. By doing so, the moving charge is losing its electric potential energy. Upon leaving the circuit element, the charge is less energized.

The location just prior to entering the light bulb or any circuit element is a high electric potential location; and the location just after leaving the light bulb or any circuit element is a low electric potential location. Referring to the diagram above, locations A and B are high potential locations and locations C and D are low potential locations. The loss in electric potential while passing through a circuit element is often referred to as a voltage drop.

Volt The volt symbol: V is the derived unit for electric potentialelectric potential difference, and electromotive force. The volt is named in honour of the Italian physicist Alessandro Volta —who invented the voltaic pilepossibly the first chemical battery.

## Electric potential, voltage

Hydraulic analogy A simple analogy for an electric circuit is water flowing in a closed circuit of pipeworkdriven by a mechanical pump. This can be called a "water circuit". Potential difference between two points corresponds to the pressure difference between two points.

If the pump creates a pressure difference between two points, then water flowing from one point to the other will be able to do work, such as driving a turbine. Similarly, work can be done by an electric current driven by the potential difference provided by a battery. For example, the voltage provided by a sufficiently-charged automobile battery can "push" a large current through the windings of an automobile's starter motor.

If the pump isn't working, it produces no pressure difference, and the turbine will not rotate. Likewise, if the automobile's battery is very weak or "dead" or "flat"then it will not turn the starter motor. The hydraulic analogy is a useful way of understanding many electrical concepts.

• 7.2: Electric Potential and Potential Difference
• Electric Potential Difference
• Electric potential

In such a system, the work done to move water is equal to the pressure multiplied by the volume of water moved. Similarly, in an electrical circuit, the work done to move electrons or other charge-carriers is equal to "electrical pressure" multiplied by the quantity of electrical charges moved.

In relation to "flow", the larger the "pressure difference" between two points potential difference or water pressure differencethe greater the flow between them electric current or water flow. See " electric power ". Working on high voltage power lines Specifying a voltage measurement requires explicit or implicit specification of the points across which the voltage is measured.