Electrocution Anatomy

Electricity is an omnipresent force, both useful and dangerous. It's an aspect of modern life that we encounter daily, whether it's that annoying static shock from a carpet, a nasty zap from tinkering with electrical circuits, or even witnessing the dire consequences of an electrical accident. The term 'electrocution,' which succinctly describes death resulting from electric shock, is a portmanteau formed from 'electric' and 'execution.' Interestingly, the word originated in 1889 when William Kemler of Buffalo, New York, was found guilty of murdering his common-law wife, Matilda Ziegler, by striking her 26 times in the head with a hatchet. The execution method employed was the electric chair, also known as 'electric execution.' A New York Times journalist creatively coined the term 'electrocution,' and it has since become the standard term for such fatalities.

Understanding the science behind electrocution is essential because it involves a complex interplay of various factors that ultimately determine its lethality. Electricity, in its essence, involves trillions upon trillions of electrons that are propelled through a material by an electric field. As this electric field pushes these electrons, it strips them from their atoms, specifically valence electrons, which have a tenuous connection to the atom's nucleus. The process of electricity can be explained by a simple example: inserting a strip of zinc and copper into a potato, connecting them with a wire and an LED. This setup generates an electric current by pushing electrons towards positively charged copper ions, thereby creating a flow of electrons, which constitutes electricity. Nevertheless, even in such a seemingly straightforward setup, there are trillions of electrons in motion through the wire. For example, one milliamp of current, a current level barely perceptible to human senses, involves a staggering 6.24 quadrillion electrons moving across the wire per second. These electrons, as they course through a material, engage in countless collisions with copper atoms, ions, and other electrons, a process that generates friction, leading to heat. This process resembles the way heating coils in toasters operate – electrons traverse the wire, their collisions causing friction, which subsequently produces heat, making the coil glow red-hot, enabling you to turn bread into toast.

It's worth noting that certain materials serve as excellent conductors of electricity due to their loosely bonded electrons on the outermost orbital, which permits them to be pulled off easily. This property allows atoms in materials like copper, aluminum, gold, and silver to facilitate electron flow with minimal impedance. Consequently, copper, aluminum, gold, and silver wires have minimal impedance to electron flow, which makes them superb conductors of electricity. It's noteworthy that the human body's nervous system is an excellent conductor, designed to send electrical signals to muscles. On the flip side, some materials act as insulators, significantly inhibiting electron flow. Common insulators include rubber, plastic, and glass. These materials contribute to more friction for electrons due to their atomic structure, which lacks free electrons. Electricity demands extra energy to traverse insulators because of this heightened friction. This is why conductive copper wires are often coated with rubber to prevent electricity from leaking out of the wire.

Transforming an insulator into a resistor is a matter of adjusting its properties to slightly decrease its resistance, thereby allowing some electrons to flow. Resistors, in electrical circuits, serve the purpose of reducing voltage for downstream components, preventing them from being damaged by excessive voltage. The skin, under regular circumstances where it's dry and intact, acts as an insulator, offering a resistance of approximately 100,000 ohms. When electricity passes through the skin, this high resistance generates heat. In conditions where the skin is dry, the energy required to force electricity through the highly resistant skin results in severe burns, alongside a slow and painful execution. This characteristic of skin resistance becomes particularly relevant in the context of electric chair executions. During these executions, a sponge soaked in saltwater was placed under the cap on the prisoner's head. This served to lower the skin's resistance, ensuring that electricity could pass more effectively. By reducing resistance, the execution process was expedited, preventing severe burns and accomplishing a quicker, more humane execution.

When it comes to electricity, it's essential to recognize that both voltage and current play pivotal roles in its effects on the human body. Some individuals incorrectly argue that only current is responsible for causing harm, but in reality, both voltage and current work in tandem to produce the lethal effects. This misconception arises because current is often defined as the number of electrons moving per second. However, it's crucial to emphasize that you can't have current without voltage. Voltage serves as the pressure acting on the electrons, while current denotes the quantity of electrons moving through a circuit per second. A simple analogy for this relationship can be drawn from the flow of water through a pipe. In this analogy, voltage equates to the water pressure, while current is the number of water molecules passing through the pipe every second. Notably, in the human body, electricity follows the path of least resistance, and this usually means the nervous system, as the nerves are adept at conducting electrical signals.

Electrocution leads to two primary effects on the human body: thermal burns and nerve disruption. The extent of damage varies according to the amount of electrons flowing through the body per second, which, as mentioned earlier, technically constitutes current. Various levels of current result in distinct physiological responses, and the associated effects can range from a mild sensation to fatality.

One Milliamp of Current: At this level, the current is typically too low to cause any pain, manifesting as a slight tingling sensation on the skin. Although it's not immediately dangerous, this level of current can become uncomfortable over time.

Six Milliamps of Current: This level induces an uncomfortable and mildly painful vibrating sensation. Some have described it as feeling like painful internal tremors that travel from the hand to the arm.

15 Milliamps of Current: This is where the potential for lethality begins. At 15 milliamps, the electric field generated by the current is potent enough to induce forced muscle contractions. This phenomenon is termed the "no-let-go threshold" because muscles contract involuntarily, and the affected person finds it nearly impossible to release their grip on the electrical source. While 15 milliamps may not instantly lead to death, it can result in fatal burns if no one is present to intervene.

50 Milliamps of Current: At this level, current passing through the chest can lead to respiratory paralysis, causing the cessation of breathing. Muscular contractions also become significantly more severe, potentially causing further complications and damage. Even if the shock is brief, this level of current can lead to severe internal and external burns.

100 Milliamps of Current or Higher: Current at this intensity is fatal with a single shock. Such high levels of current disrupt sodium and potassium ion channels in the heart's electrical signaling system, resulting in ventricular fibrillation. This chaotic and uncoordinated rhythm in the ventricles prevents the heart from pumping blood, and death can occur within minutes.

These thresholds illustrate the critical role of current levels in electrocution. However, it's important to highlight that both voltage and current contribute to the lethal effects. Although some argue that current alone causes harm, this is not accurate because voltage provides the necessary pressure to drive the flow of electrons (current).

The discussion thus far has centered on direct current (DC), but it's vital to note that alternating current (AC) is the dominant form of electricity used in most industrial and residential power systems. AC is particularly dangerous due to its oscillating nature. While DC features a continuous and constant flow of electrons, AC oscillates, altering its intensity based on the position of the magnetic field generating it.

The oscillations in AC make it more lethal at lower current levels than DC. The manner in which AC is generated further explains its distinctive properties. AC is generated by rotating a magnet inside a loop of copper wire. The magnetic field induces a back-and-forth flow of electrons in the wire. If the AC has a frequency of 60 hertz, this means the current turns on and off 60 times every second. This rapid oscillation results in muscles contracting and relaxing 60 times per second. This continuous and rapid muscle contraction and relaxation cause significant damage to muscles, including the heart, potentially leading to fractures of bones due to the muscle contractions.

In AC, even small amounts of current can be lethal. A mere 30 milliamps of AC is sufficient to pose a serious threat. This heightened danger is the reason why AC is preferred for electric chair executions, as it requires lower voltage levels to achieve the desired lethality. Electric chairs deliver around 2,000 volts of AC through the prisoner's cranial cavity, causing electrical damage to the brain and central nervous system, leading to rapid unconsciousness and death. The execution procedure involves turning the AC on and off in a specific pattern to ensure the efficient execution of the prisoner.

In conclusion, the anatomy of electrocution encompasses a complex interplay of various factors, including voltage and current levels. These factors determine the extent of damage and, ultimately, whether electrocution is fatal. Understanding the interplay between voltage and current and the consequences of electrical shock on the human body is essential for promoting electrical safety and mitigating the risks associated with electricity.