Using Ohm’s Law to Calculate Amp Draw|
Article - February, 2016 By LarsonElectronics.com
Using Ohm’s Law to Calculate Amp Draw
Many years ago, in a High School Physics class, we were introduced to Ohm’s Law. Simply put, Ohm’s Law states “The resistor's current I in amps (A) is equal to the resistor's voltage VR=V in volts (V) divided by the resistance R in ohms (O):” To most, it’s as confusing today, as it was the first time we heard it. By breaking it down, piece by piece, you can use this nifty tool to calculate the amp draw of nearly all electronic equipment, including LED lights.
To accurately figure the amp draw of any equipment, you will need 2 pieces of information. First, you need to know the voltage (V) going to the equipment. The voltage may be listed as 120V AC, meaning 120 volts of alternating current (standard household current), or 12V DC (standard battery current or from an AC/DC power transformer). The second piece of information you need is the wattage output of the electronic equipment you will be using. You can usually find this information listed on the product label, or in the owner’s manual. Then you take the wattage, and divide it by the voltage (100 watts / 12 volts = 8.33 amps.) This will tell you roughly the amperage your equipment will draw. You can use this date to determine if your power source is capable of adequately powering your electronics.
So while it may seem to be a daunting task, even the most novice electronics buyer can use Ohm’s Law to decide which products will work together. As in all purchases, taking time to research a product’s requirements and abilities will pay off in the long run. Once again, another instance of using science to simplify life!