Short Circuit—you know, the movie with the cute little robot? Wait, not that kind! Short circuits are actually really important in STEM because they can be really problematic.

Lesson Objectives:

In this lesson you will:

• Learn what a short circuit is and how it occurs.
• Explore Ohm’s Law when current travels through a circuit with no resistance.
• Learn how to prevent a short circuit from occurring.

A “short” is a connection in a circuit that isn’t intended—this occurs when the path of the circuit has very little, or no,  resistance. Why would this be a bad thing? Let’s take a look at Ohm’s Law and we can see why. We know that Ohm’s Law relates voltage, current, and resistance— I=VR. There isn’t really any problem with this equation unless we divide by 0… We know that you can’t divide by 0!

If you know a little bit of calculus, you can instead take the right-hand limit of Ohm’s Law. If you don’t know calculus, that’s ok too! All this does is show us what happens on the graph when we get really really close to 0 resistance. It shows us that our current goes to infinity. Infinite current is not a good thing!

A short like this can cause your wires to overheat, your electronic components to burn or catch fire, and, if you’re using a chemical battery, it could even combust.

Now, you’re probably wondering: “what does a short look like?” Well, we’ve gone ahead and created a short in graphite—the same stuff that you would have in your pencil. Don’t try this at home—it could end badly! As you can see in the video, shorts can produce heat, fires, cause electric shock, and so much more!

The best way to avoid the problems a short causes is to avoid a short! Make sure that you don’t create any live connections that have little to no resistance going through them. Shorts can occur through any conductor, so be sure to also avoid keeping liquids, metal shavings, or anything else like that near your electronics.