How to Prevent Metal Surfaces From Shocking You
By: Kelvin Winter
Tags: Life Hacking, Winter, Physics, Electricity, Science

An unassuming doorknob (Unsplash.com)

Tired of getting shocked when you try to get into your car or open the front door to your office? Here’s a useful trick that I learned a few years ago that comes in handy especially in the winter months. I’m not the first to discover this; there are many articles online that also talk about it. But since none of my friends or coworkers seemed to know about it, I wanted to write a short article on how it works and the underlying science. It’s a very simple technique and doesn’t require any sort of investment other than a metal object.

Basically, all you need to do is take a small metal object, such as a key or coin (I’ll use a key as an example for the rest of the article), and touch it to the metal surface that you think will shock you. Normally, if your body is statically charged and you touch a metal surface with your bare finger, a spark will jump between the tip of your finger and the metal. The same process occurs when you touch a key to the metal surface, but in this case, you won’t feel a shock. This is because the metal key is a very conductive material and helps act as an extension of your body. Electrons are transferred from your body to the key and to the metal surface. The more surface area of your finger that is in direct contact with the metal portion of key, the less likely you will feel the shock, since the energy flowing from your body to the metal (the key in this instance) is distributed evenly across all areas where the metal of the key and the skin of your finger are in direct contact. The reason a spark hurts so much when you touch a metal surface directly with your finger is because all of that concentrated energy from the spark is transmitted directly from a very small area at the tip of your finger. This stimulates the nerve endings at the tip of your finger, leading to the pain of a shock. This problem with surface area is eliminated when you use a key since it becomes an extension of your finger and takes the direct hit from the spark.

A spark jumping between a key and metal lock. If I had touched the metal lock directly with my finger instead of the key, I probably would have experienced a painful shock.

Here’s a few tips to keep in mind. Make sure your finger is directly touching the metal portion of the key. If you have a car key with a plastic grip, holding only the plastic portion won’t be effective since plastic is a poor conductor of electricity and electrons won’t be able to flow between your finger and the key effectively enough. This could lead to a surprise shock if you touch the metal surface directly with your finger thinking you’ve successfully discharged yourself. Remember, the more area of your finger that is in contact with the metal portion of the key, the less painful the shock will be. Usually you can tell if it was successful if you can hear a spark or feel the hair on your arm jump but don’t feel a shock. If you followed these steps and nothing happens, then that means that you probably wouldn’t have been shocked to begin with, so it should be safe to touch the metal surface directly. Enjoy!