Will Electricity Pass Through Water?

Imagine you are out swimming in the ocean on a stormy day. Suddenly, a bolt of lightning strikes the water just a short distance away. You feel a tingling sensation as electrical current from the lightning passes through the water around you. Though it only lasts a split second, it serves as a vivid reminder that water and electricity can interact under certain conditions.

Water itself does not conduct electricity very well. However, depending on factors such as salinity and impurities, water can allow electricity to pass through it to varying degrees. This explains how electricity from lightning can travel through bodies of water such as the ocean. By examining water’s electrical properties and the factors that impact them, we can better understand when and how electricity flows through water.

Basics of Electricity

Electricity is the flow of electrons through a conductive material. Atoms contain positively charged protons in their nuclei and negatively charged electrons orbiting around the nuclei. Materials that allow electrons to move freely are called electrical conductors. Metals like copper and aluminum are good conductors. In contrast, insulators like glass, rubber and air do not readily allow electron flow. When an electrical voltage is applied across a conductor, it creates an electric field that exerts force on the electrons, causing them to drift through the material. This electron drift creates an electric current. Therefore, electricity flows through conductive materials when electrons can freely move through them.

Water’s Electrical Conductivity

The ability of water to conduct electricity depends greatly on the amount of dissolved salts and impurities present. Pure water, such as distilled water, is actually a very poor conductor of electricity. This is because water molecules alone do not readily allow electricity to flow through them.

However, when salts like sodium chloride and other charged particles dissolve into water, they produce free ions that enable the water to conduct electricity. The more dissolved salts in the water, the higher the conductivity. Seawater, for example, with its high salt content, is an excellent conductor of electricity.

Factors Affecting Conductivity

The ability of water to conduct electricity depends on several key factors:

Mineral Content

Pure water is actually a poor conductor of electricity. The conductive ability of water increases along with the amount of dissolved salts and minerals such as sodium, chloride, calcium, and magnesium ions. More dissolved ions allow electricity to flow more freely.

Temperature

As temperature rises, the movement and vibration of water molecules increases. This greater molecular activity enhances conductivity and allows electrical current to flow more easily through warm water versus cold water.

Salinity

The salt content, or salinity, also directly impacts the conductivity of water. Ocean water, being saltier than freshwater, is a much better conductor of electricity due to its higher ion concentration.

Electricity in Freshwater

Freshwater has a relatively low conductivity, which limits how much electric current can flow through it. Pure freshwater has a very high resistance, making it an insulator rather than a conductor. Most freshwater sources contain some impurities which allow a small electric current to flow.

The purer the water, the lower its conductivity. Distilled water has extremely low conductivity, while tap water’s conductivity depends on its mineral content. Rivers and lakes have more dissolved salts, allowing greater current flow. However, the conductivity is still low compared to seawater.

Even with impurities, freshwater cannot conduct nearly as much electricity as metals. The current flow is limited and localized. For this reason, electricity poses less of a hazard in freshwater environments compared to seawater, where the high conductivity enables electrical current to spread over greater distances.

Electricity in Seawater

Seawater is an extremely good conductor of electricity due to its high salt content. Sodium and chloride ions, which make up the salt in seawater, enable the movement of electrical charge. The ocean’s salinity averages around 35 parts per thousand globally, with the highest salinity found in enclosed seas such as the Red Sea. Such high salinity levels allow electricity to be transmitted easily through seawater.

Seawater is much more conductive than freshwater, by about a factor of 5. This is why offshore wind farms, ocean current turbines, and other marine renewable energy devices can efficiently transmit the electricity they generate back to land via subsea cables. The high conductivity also allows for equipment communication and data transfer underwater. Submarine fiber optic telecommunications cables laid along the seafloor rely on seawater to carry electric currents.

While seawater’s high conductivity facilitates the transmission of electricity, it also increases the risk of electrical shock drowning. When an electrically charged object, like a boat or dock ladder, leaks current into the surrounding seawater, the electricity can spread over a large area and paralyze nearby swimmers. Safety precautions are important when working with electricity near seawater.

Applications

Knowing if electricity passes through water is relevant to several practical applications. These include:

Underground Power Cables

Underwater power cables carry electricity across bodies of water. The cables are insulated so the current stays within the cable. If the insulation fails, electricity could leak into the surrounding water. This poses an electrocution risk to marine life and humans.

Electric Eel Hunting

Electric eels produce their own electricity to stun prey. Indigenous peoples of South America historically hunted electric eels by touching them with metal rods in muddied waters. The eel would discharge its electricity into the water to electrocute the hunter. Understanding how water conducts electricity was key to avoiding injury.

Risks of Swimming During Lightning

Lightning can electrocute swimmers. Though the human body has some resistance, water provides a path for electricity to flow through the body. It is unsafe to swim outdoors during lightning storms. Getting out of the water mitigates the risk.

Safety Precautions

When it comes to electricity and water, safety should always be the top priority. There are several precautions that should be taken to avoid electrocution hazards:

Avoid water during lightning storms – Being in water during a lightning storm presents a major electrocution risk. It’s critical to get out of pools, hot tubs, lakes, oceans, and other bodies of water when thunderstorms are in the area. Lightning can travel through plumbing and water to electrocute people inside.

Install a pool ground – For permanent pools like in-ground pools, a pool grounding system should be installed. This provides a path for electricity to safely travel into the earth instead of through swimmers’ bodies.

Use GFCIs – Ground fault circuit interrupters (GFCIs) are essential safety devices for any outlet near water. GFCIs detect leaks in electrical current and immediately switch off power when there is an imbalance. This helps prevent shocks. GFCIs should be installed on pool equipment like pumps.

Exercising caution around water and electricity can help reduce accident risks. With proper precautions, the dangers can be avoided.

Experiments

Here are some simple experiments you can do at home to visualize electricity flowing through water:

Saltwater Battery

Fill a glass with saltwater. Insert a copper wire on one side of the glass and a zinc coated wire on the other side without letting them touch. Connect each wire to an LED light bulb to complete the circuit and observe the light bulb glowing. This demonstrates how the sodium and chloride ions in saltwater allow electricity to flow.

Electric Celery

Cut the bottom off a stalk of celery and place it in water mixed with food coloring. Insert a copper wire and zinc wire into either side of the stalk without touching. Connect the wires to an LED light to complete the circuit and observe the light bulb illuminate. The nutrients and minerals in the celery stalk conduct the electric current and power the light.

Static Electricity

Rub a balloon on your hair to charge it with static electricity. Turn on a stream of tap water and bring the charged balloon close to the stream. The electrons on the balloon will cause the stream of water to bend towards the balloon, demonstrating the conductivity of water.

Conclusion

In summary, electricity can pass through water under certain conditions because water contains minerals and impurities that allow it to conduct electricity to some degree. The level of conductivity depends on factors like the amount of dissolved salts and impurities in the water. Seawater is much more conductive than freshwater due to its salt content. There are important safety considerations around water and electricity, like never using electrical devices in the rain, near pools or in other wet conditions. Understanding water’s general conductivity along with the influencing factors allows us to properly handle electricity around water and make use of conductivity in applications like electrofishing.