eli5 How does an Electric Eel shock you? Don’t you need to complete a circuit for the current to flow through you?

Question

If the Eel is the positive terminal, where’s the negative terminal? If you’re grounded by the water, would that mean the Eel can only shock you if you are in the water too? If the water is the final destination, why wouldn’t the current directly go from the Eel to the water? Why would it take a high resistance path through your body?

In: Physics

Answer 1

Electric eels generate electricity through specialized organs called electrocytes. These cells work similarly to batteries, with a negative and positive charge on each side. When the eel decides to discharge, it aligns these cells in such a way that a current is created along its body¹.

In water, the eel is not the only positive terminal; the electric organ discharges create a potential difference between the eel and the water around it, effectively making the water the negative terminal. When you’re in the water with the eel, your body can become part of this electric circuit. The current prefers the path of least resistance, which is usually through the water. However, if your body provides a path that’s more conductive than the surrounding water, the current may flow through you.

The reason the current doesn’t go directly from the eel to the water is that the water itself is not a perfect conductor. The current will spread out in all directions and will take all available paths according to their respective resistances. If your body is in the water, it becomes one of the many paths the current can take. Since the human body is mostly water and contains ions, it’s quite conductive, and thus, a significant amount of current can flow through it if you’re close enough to the eel.

The severity of the shock you’d experience depends on how much of the current passes through your body, which is influenced by your distance from the eel, the conductivity of the water, and your body’s resistance compared to the water’s resistance¹. Electric eels use this shocking ability to defend themselves and to stun prey, making it easier to capture². They can control the intensity of the electric discharge, using lower voltages for navigation and communication, and higher voltages for defense and hunting².