What Are the Differences Between Amps, Volts, Watts？

Amps, volts, and watts are three basic concepts you will repeatedly deal with when working on any electrical system. A fourth being resistance which is measured in ohms. It may seem overwhelming, but you don’t need an engineering degree to understand what electricity is and how to use it to your advantage.

Similar to how water flows through a hose, electricity is the flow of electrons through a conductor. In most electrical systems, the conductor is a wire.

Since you can’t easily see electrons, we’ll use a water and hose analogy below. Let’s jump into it by explaining each concept on its own.

What Are Amps?

The ampere, or amp for short, is the unit of measure for electrical current. Current is the speed or rate at which the electrons flow through a conductor and is represented by the letter “I” in electrical equations.

In our water analogy, electrical current is equivalent to the flow rate or amount of water flowing through the hose. 

What Are Volts? 

Volts are the unit of measure for electrical voltage and are represented by the letter “V” in electrical equations. Voltage is the difference in electrical potential, or the number of electrons, between any two points in an electrical circuit. 

In our water analogy, voltage is equivalent to water pressure. Pressure is the force that moves the water through the hose, just like voltage pushes electrons through a conductor. 

What Are Ohms? 

Ohms are the unit of measure for electrical resistance in a conductor and are represented by the letter “R” in electrical equations. Resistance tries to slow down the flow of electrons. 

In our water analogy, resistance is the diameter of the hose. A wide hose has very little resistance and allows water to flow through it quickly. Conductors with low electrical resistance, like copper wire, allow electrons to flow easily through them, just like the wide hose. 

What Are Watts?

Power is the rate at which electrical energy is transferred in a circuit and is measured in watts. In electrical equations, the letter “P” represents power.

Power is a little harder to explain using the water analogy. With a hose, you can increase the power by either increasing the amount of water coming out or increasing the water’s pressure coming out. In an electrical system, you can increase the power by increasing the current or increasing the voltage.

Bringing It All Together

It’s important to understand these basic concepts on their own, but the real fun happens when we tie amps, volts, and watts all together.

Voltage, Current, Resistance

Ohm’s Law relates voltage, current, and resistance. It is represented by a simple equation. 

V = I * R

V = voltage (volts)
I = current (amps)
R = resistance (ohms)

If you keep the resistance the same and increase the voltage, the current has to increase. Like in our hose analogy, if you increase the pressure, then more water will flow through it.

Resistance works against voltage to slow down the flow of electrons. If resistance increases while the voltage stays the same, the current flowing through the circuit will decrease. Similarly, if you pinch the hose to create a smaller diameter or increase the resistance, less water comes out of the end.

Power, Current, and Voltage

To bring together watts (power), amps (current), and volts (voltage), we need one more simple equation. 

P = V * I

P = Power (watts)
V = voltage (volts)
I = current (amps)

Looking back at our example of water flowing through a hose, we can now see how power is directly related to current and voltage using this equation.

For example, imagine that you’re spraying the hose to turn a water wheel. The faster the wheel turns, the more power is generated. 

If the hose size remains the same, we can make the wheel turn faster in two ways. The first is to increase the flow rate, which means more water and weight are hitting the wheel and spinning it faster. The second way is to increase the water pressure so that the water is hitting the wheel with more force and turning it faster.

In our analogy, the water flow rate is equivalent to current and water pressure is equal to voltage. As the equation above shows, if you increase either the current or the voltage, your power will also increase.

The relationships between power, current, voltage, and resistance seem overwhelming at first, but they’re pretty simple once you dig in. Now that you have a basic understanding of the fundamentals of power and electricity, you should be able to tackle your RV electrical projects with a little more confidence.

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