Close
today i learned (til)

Understanding Static Electricity

January 23, 2020

A Normal Winter Night

It’s a cold winter night, you’re snuggled up in your favorite blanket sitting on a couch and watching TV, the heater doing its best to prevent the winter winds from disturbing your moment of Zen. You’re thirsty, craving the delicious nature of nice, hot chocolate. So, you get up, placing your fluffy socks on the carpeted floor, blanket wrapped, and head towards the kitchen; however, on your way, you have to go through a closed door, and brace yourself against the icy, wooden floors that is your kitchen. As you take the courage to confront the chilly adversary and reach your hand to the metal knob, you feel a jolt of energy against you, a loud SNAP, and a flash of lighting going from your hand startles you, bringing about a moment of pain. Feeling betrayed, worried, you try again. What you felt was the power of static electricity, something that we’ve all experienced in one form or another.

What is Static Electricity?

Static electricity is a common occurrence in life. From rubbing an inflated balloon on your furry pet to rubbing socks on a carpeted floor, the friction between two objects (normally insulators such as fur, plastic, or clothing) causes electrons to move from one object to another. This creates a difference of charge, or electrostatic potential. When there is enough energy to match this electrostatic potential, the electrons will move. Think of it like this: every molecule wants to wants to be in balance, and whenever there is an imbalance, those molecules will do what is necessary to return to said balance, but need the energy to do so. In the example above, your covered feet rub against the carpet and collect electrons that spread throughout your body – this makes you negatively charged, or “electron rich”. Metal – the door knob – is typically positively charged, or “electron deficient”, and therefore wants to take any electrons it can get. When the two objects get close enough, there is less energy required for the electrons to move (imagine trying to move a ball far away from you compared to right next to you… much easier, right?) and so they do. This causes for that “flash” to be seen from your fingertip to the door knob, and the pain you feel is caused by the sudden movement of electrons (look at E-Stim, my other article, it talks a bit about the human body and electricity… this isn’t advertisement, I swear!)) that then trigger nerve receptors, the more electrons that move, the stronger the feeling.

So, how does all of this tie in with exploding gas? The answer, my dear friend, is one word: combustion. Combustion is the reaction of oxygen, a fuel source, and energy, as seen in the formula for the combustion of rubbing alcohol below:

Equation

But wait, what’s a reaction? Remember what I said before about molecules doing whatever it takes to return to balance? Well, that’s a reaction! When atoms combine to form molecules, they use energy to form bonds to stick together and reach a form of balance. In order to break these bonds, more energy is required, and atoms separate and join with other atoms nearby to form new molecules. This causes for energy to be, in this case, released. This is used in your cars to move pistons and make your car move, but that’s another lesson. Now, imagine your clothes rubbing against your seat when you’re getting out of the car to fuel up or after getting something. Considering that the fuel nozzle is metal, that gasoline has a tendency to become a gas, and you have a charge build up… since energy is made from the movement of electrons (they literally crash into other atoms when they move) it causes for this reaction to occur, and now the expansion of heat and air spread out and cause those explosions that many people see in horror movies.

As electrons move from the hand to the metal, they can collide with gas vapors.
As electrons move from the hand to the metal, they can collide with gas vapors.

 

But how do we counter this?!

It’s actually pretty simple: touch your car before you touch the nozzle. The extra electrons on your clothes and body will go to the car, and then to the ground instead of to the gasoline vapors near the nozzle. Make sure to do this a ways away from your gas tank – ideally by the doorframe by the driving wheel, and you should be fine!

Either way, there are other ways for energy to be transferred, so you need to always be careful when going near a fuel source. Just don’t smoke, use flint, or summon the power of the force while you’re gassing up. Be smart, and don’t do anything that might cause for combustion to occur!

 

 

Electric Potential Energy. (n.d.). Retrieved April 14, 2018, from http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elepe.html

E., E., E., E., E., & E. (n.d.). Electricity – Electrical Charge, Electric Fields, Coulomb’s Law And The Forces Between Electrical Charges, Resistance – Current, Voltage, Ohm’s law. Retrieved April 14, 2018, from http://science.jrank.org/pages/2342/Electricity.html

Combustion. (n.d.). Retrieved April 14, 2018, from https://www.grc.nasa.gov/www/k-12/airplane/combst1.html

Combustion Reactions. (n.d.). Retrieved April 14, 2018, from http://www.iun.edu/~cpanhd/C101webnotes/chemical reactions/combustion.html

 

0Likes
Lee Wilkes
About Author

Lee Wilkes II is an undergraduate at Georgia Tech studying Biomedical Engineering. He enjoys learning about new cultures, plays 4 instruments, and loves Asian food.

You May Also Like

today i learned (til)
Fast Fashion and Greek Life: Overconsumption in Style
today i learned (til)
Can Algorithms Deliver Justice?
collage of radio elements, birds on telephone line, vinyl in top left, play buttons, sound wave vectors
today i learned (til)
“College Radio : It’s Not Dead”
today i learned (til)
Why did so many people not comply with evidence – based guidelines and precautions set during the Pandemic? Science implies that it may be due to Mirror Neurons!

Your journey starts here! Let’s talk!

ThemeRex © 2026. All rights reserved.
  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.