Amps and Watts and Volts, Oh My!
(Writer’s note: My apologies to the composer of the “Lions and tigers and bears, oh my!” from the Wizard of Oz.)
Obviously, our daily lives would be inconceivable without electricity. Today, almost everything involves the use of electrical energy. Moreover, the increasing use of electricity is an important requirement for the continuing and swift expansion of industry, from agriculture to warehousing and everything in between.
Minus the application of electrical energy, there would be no television, broadcasting, or even telecommunication. What’s more, heating and cooling systems, home entertainment centers, laptops, electric ovens, and most other appliances would be obsolete. Put simply, the significance of electricity cannot be overestimated.
Anyone who has purchased any manner of electrical apparatus must have encountered the terms amperage (amps), wattage (watts), and voltage (volts). Regrettably, not every homeowner knows or appreciates the significance of these terms.
Let’s face it. As just mentioned, so much of our daily lives run on electricity, yet many of us don’t know the difference between a 60-watt and 75-watt light bulb or how voltage from the wall socket supplies enough juice to run both a small desk lamp and a powerful microwave.
Having at least a basic understanding of watts, amps and volts not only makes you an informed consumer but can actually allow you to save a substantial amount of your hard-earned cash on your monthly energy bills.
What is a volt?
Voltage is a measurement of the electric potential or “pressure” at which electricity moves through a system. Voltage is also defined as the speed of single electrons as they move through a circuit and is measured in units called volts.
In the United States, power from the electrical grid is provided to homes at two different voltages:120 volts and 240 volts. That’s due to the fact that various home appliances operate at different voltages. Large, energy-ravenous appliances such as air conditioners or clothes dryers operate at 240 volts, while most other devices, such as light bulbs, TVs, computers, and cell phone chargers, only require 120 volts.
In short, volts are typically considered “the pressure” of electricity – -the higher the volts, the more pressure it has.
By the way, volts are named after the Italian physicist Alessandro Volta, who built one of the first batteries in 1800.
What is an amp?
Amperage is just one more way to determine the amount of electricity running through a circuit. Amperage is the “rate” the current is flowing through the circuit or the number of electrons traveling through the wire. Amperage is listed in units called amps.
You probably will come upon amps if you peek inside your home’s service panel (also called the breaker box). You’ll observe various circuit breakers listed as 15 amps, 20 amps, and 30 amps. The higher the amperage, the more electricity can flow through the circuit. Once more, large appliances such as air conditioners and dryers will be attached to 30-amp circuits, while most additional outlets will be powered by 20-amp or 15-amp circuits.
If you try to run too many appliances on the same circuit, the breaker will “trip” and cut off power in order to prevent the wiring from overheating.
FYI: The unit is named after the French physicist Andre-Marie Ampere, one of the fathers of electromagnetism.
What is a watt?
Of all these various units of electricity, wattage is probably the most familiar to you. For years, you’ve been purchasing 40-watt and 60-watt light bulbs with the clear understanding that a 60-watt bulb is going to shine brighter than a 40-watt bulb. But why?
Wattage, it turns out, is the amount of power an electric device expends. Another way to consider wattage is “electricity at work” – the power needed to actually do something, whether it’s operating a vacuum (400 to 900 watts), ringing the doorbell (2 to 4 watts) or illuminating a light bulb (40 to 75 watts).
To determine wattage, you merely multiply voltage (pressure/speed) by amperage (volume), expressed as V x A = W. The faster each electron moves through the circuit and the greater the volume of that circuit, the higher the wattage.
Wattage is measured in units called watts after James Watt, the Scottish engineer who popularized the steam engine.
Here are the wattage ratings of some common appliances:
Ceiling fan: 60 to 70 watts
Clothes dryer: 1,000 to 4,000 watts
Coffee maker: 500 to 1,000 watts
Dishwasher: 1,200 to 1,500 watts
Washing machine: 500 to 800 watts
Electric stove: 2,000 to 3,000 watts
Garage door opener: 300 to 400 watts
Microwave: 600 to 1,700 watts
Phone charger: 4 to 7 watts
What are ohms?
Gotcha, you thought we were all done. So far, we’ve talked about various ways to measure the amount of electricity flowing through a circuit and the amount of wattage that’s required to run different electrical devices linked to that circuit.
Electrical wiring used in construction is made of materials like copper and aluminum. While good conductors of electricity, these materials have a definite amount of natural resistance or friction, which reduces the flow of electricity. When electricity passes through various electrical devices and appliances, they also employ their own resistance.
This resistance is measured in ohms which are named after the German physicist and mathematician Georg Simon Ohm.
Still a bit confused? Perhaps this analogy will help clear things up a bit.
A water pipe analogy
Amps, volts, and watts are three basic concepts you will frequently deal with when talking about an electrical system, with a fourth being resistance which is measured in ohms. It may seem a bit overwhelming, but you don’t need an engineering degree to be familiar with what electricity is and how to use it to your advantage.
Start by picturing water flowing within a closed system, such as a water pipe. The circuit made by the water corresponds to electrical flow. Electricity, much like water, travels in an uninterrupted circular fashion through a conductor, such as a wire. Each individual electrical term – amps, volts, watts, and ohms – plays an important role in this flow of electricity.
In our water analogy, amps would be equated to the volume of water moving past any certain point at a particular moment.
Within this electrical circuit, amps measure the electrical current or the volume (not speed) of existing electrons. On the other hand, a voltage can be compared to water pressure. Volts denote the speed at which electrons pass a precise point within a closed circuit.
So, what’s the difference between amps and volts? Amps and volts operate in harmony with one another with their own clear-cut roles. An ampere is a measure of electricity. Volts represent the difference in potential that drives amps to flow through the closed circuit. Put simply, while amps are equal to the volume of water in our pipe analogy, volts carry the water through the circuit.
What about watts? Derived from the formula V x A = W, a watt is the rate of power flow that’s actually produced. For example, if the water system described herein was used to operate a mill, watts would represent the amount of energy created to power the mill.
Finally, we have our ohm, which defines electrical resistance. Within an electrical circuit, resistance results from any material or object that reduces the flow of electricity. Ohms measure the precise amount of resistance. Within our water analogy, ohms represent pipe size. For example, less water will be able to flow through a narrow pipe than a pipe that’s wider at the same pressure. Put simply, a wide pipe is less resistant than a narrow pipe.
Bringing it all together
It’s important to understand these basic concepts on their own, but the real fun takes place when we tie amps, volts, watts, and ohms all together.
Ohm’s Law relates voltage, current, and resistance. It’s represented by a simple equation: V = I * R, where V=voltage, I=current (amps), and R=resistance (ohms).
If you keep the resistance the same and increase the voltage, the current has to increase. Like our pipe 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. Always keep in mind that the higher the resistance, the more voltage will be needed to overcome that resistance. Similarly, in our analogy, if you decrease the size of the pipe to create a smaller diameter, you’ve increased the resistance, meaning less water can flow through the pipe.
To bring together watts (power), amps (current), and volts, we need one more simple equation: P = V * I, where P=power, V=voltage, and I=current.
Keep in mind that Power = Watts.
Looking back at our example of water flowing through a pipe, we can now see how power is directly related to current and voltage using this equation.
For example, imagine you’re employing the flowing water through the pipe to turn a water wheel. The faster the wheel turns, the more power is generated. If the pipe size remains the same, we can make the wheel turn faster in one of two ways. The first is to increase the flow rate, which means more water and weight is hitting the wheel and spinning it faster. The second way is to increase the water pressure so that the water hits the wheel with more force and turns it faster.
In our analogy, the water flow rate is equal to the current, and the water pressure is equal to the voltage. As the equation will show, if you increase either the current or the voltage, your power will also increase.
Okay, how about a more practical example of our use of electricity
Grasping how these different terms relate to one another can be helpful, for example, in determining whether an existing electrical panel can sustain another appliance.
While watts are interchangeable, voltage is generally fixed. An appliance that consumes a large quantity of current, such as an electric stove, may need to be on a distinct circuit with a higher voltage. This is because it demands a higher voltage, meaning that it uses up more current per unit of time than other appliances, so it needs more voltage. Without the higher voltage, the appliance simply wouldn’t run because it would be deprived of the current it needs to be able to operate.
Understanding the association among various electrical terms can also help you assess monthly power bills. Electrical consumption is measured in watts, or watt-hours and power companies measure and bill consumption in kilowatt-hours which is equal to consuming 1000 watts of power for one hour. Most households consume hundreds of kilowatt-hours every month.
The number of kilowatts billed to each household is linked to the volts and amps. Volts remain constant, but amps change depending on the demand for current. When you switch on more appliances or run them for lengthier periods, you boost the demand for current, which in turn increases the total watts consumed. By running fewer appliances or changing to more efficient devices that demand less current, you can cut the amount of kilowatts consumed and slash your energy bills.
Okay, hopefully, you have a better understanding of electricity, how it is employed to power appliances and other devices around the home and how you can save yourself a bit of money by using it more wisely.