History of Voltage

Alessandro Volta, born on February 18, 1745, in Como, Italy, was an Italian physicist and pioneer in the field of electricity. He is best known for his invention of the electric battery, which revolutionized the study and application of electricity. Volta's interest in science began at an early age, and he pursued his passion for physics and chemistry throughout his education. He became a professor of experimental physics at the University of Pavia in 1774, where he conducted groundbreaking research and made significant contributions to the field.

In 1800, Volta invented the first true electric battery, known as the "Voltaic Pile." This device consisted of a stack of alternating zinc and copper discs, separated by pieces of cardboard soaked in saltwater. The Voltaic Pile produced a steady flow of electric current, which was a remarkable achievement at the time. Volta's invention demonstrated the concept of a continuous flow of electricity, challenging the prevailing belief that electricity could only be produced by static sources like friction or by using chemical reactions in isolated instances. The Voltaic Pile laid the foundation for the development of practical electrical circuits and devices.

Volta's achievements garnered widespread recognition, and he received numerous honors during his lifetime. In 1819, the unit of electrical potential difference, the volt, was named in his honor as a testament to his groundbreaking work.

Voltaic Pile

The Voltaic Pile, invented by Alessandro Volta in 1800, was a groundbreaking device that revolutionized the field of electricity. Consisting of a stack of alternating zinc and copper discs separated by electrolyte-soaked cardboard. When stacked like this, one metal will want to remove electrons and the other will want to receive them. The Voltaic Pile generates a steady flow of electric current and a single set of these metals and electrolyte sheets is called a cell. This invention marked a crucial turning point in understanding electrical energy and laid the foundation for the development of practical electrical circuits and devices. With this invention, Volta proved that electricity could be generated chemically and debunked the prevalent theory that electricity was generated solely by living beings. Volta's innovative creation paved the way for advancements in technology, communication, and countless other areas that continue to shape our modern world.

What is Voltage?

Voltage is defined as the difference in electric potential between two points. The interaction of these points in trying to equalize and move their difference in what is known as charge from high potential energy to the point with lower potential is voltage. This difference in charge between two points is what is measured as volts.  

Voltage as Pressure

When talking about voltage, or electric potential and pressure, it is easy to make an analogy to water because water also has potential energy and pressure and we can see it, unlike electricity. Water towers create water pressure by being built on higher ground than the homes we live in. Water towers take advantage of the potential energy created by this difference in height and can be calculated with the formula: Potential Energy = Mass (of the water) X Gravity X Height. If more water pressure is wanted engineers can change the level of the water (mass) or the height of the water tower. By changing either of these two, they can create the needed water pressure for the homes nearby. 

Focusing just on the level of water in the tank makes the comparison with voltage even easier to see. Think of Voltage as the height of the water in the tank. In this example, everything else in the system will stay the same except for the height of the water. This is analogous to voltage change. 

Here, our tank is almost full. Notice the pressure gauge on the pipe as the water flows. With the water tank mostly full, the pressure is high and has high potential energy.

When the level of the water level is lower and the level of water is less, the pressure shown on the gauge is also lower because the water has a lower potential energy.

If we replace the water with a voltage we can continue this analogy. Each orange circle is equal to one volt. Looking at a full tank of voltage we can read the gauge. However the measurement tool we use for measuring voltage isn’t a water pressure gauge, it is a multimeter which reads electric pressure.

With a full tank of voltage, our gauge reads high. However, with voltage, the correct gauge to measure is a voltmeter or multimeter.

The amount of force each volt is actually pushing through our pipes, which represents a circuit, is the measured voltage. Higher voltage produces a higher rate of flow of electric charge. 

As our tank of voltage is lower, so is the measured voltage from the multimeter because just like the water, the electric pressure is less.


Voltage is also known as electric potential, electric pressure, and electric tension. Because of having these multiple names starting with the word electric, you will sometimes see voltage represented as a capital E in some older textbooks. Today we commonly will use the word voltage or volts represented as capital V since E is typically used for energy. 

When looking for total voltage in a circuit, you’re actually looking for a total change in voltage between the positive and negative terminals. This can be represented by ΔV. For simplicity’s sake, we often just use V without the delta when annotating a circuit because this is understood. 

Measuring Voltage

These same measurements of voltage, or electric pressure, can be measured off a battery. In this case, let's use a AA battery. Each AA battery measures 1.5V in real life. As we know from Volta and his Voltaic Pile, the inside of each battery is made up of cells.

Depending on the material, each cell will produce a specific voltage, and when cells are stacked on top of each other in series the voltage will increase. 

We can see this when we stack two AA batteries on top of each other. When we do this, the voltage will read double because we are effectively doubling the number of cells in the stack- or to bring it back to the water example, doubling the level of water in our tank. 

Experiment with Voltage! Build a Voltaic Pile

Here is an experiment you can try at home. In this experiment, you can make your very own voltaic pile or simple battery just like Alesandro Volta. We can create a voltaic pile by stacking two dissimilar metals together and separate them with an electrolyte. At home, you can use pennies made from Copper and Nickels made from cupronickel separated by paper towels made damp from lemon juice or vinegar to act as your electrolyte. You can measure the voltage from your voltaic pile by using a multimeter. Challenge yourself to get the highest voltage you can by experimenting with different coins or objects made from different metals like zinc washers or a quarter made from nickel or by stacking your pile as high as you can! Remember, the more cells you have, the more voltage you will be able to create.