What Is Induced Voltage?

Geisha A. Legazpi

Induced voltage is an electric potential created by an electric field, magnetic field, or a current. The induced voltage in natural and man-made material is carefully planned in many disciplines, including safety and equipment protection. In the early history of electricity, Benjamin Franklin demonstrated the buildup of electrical charges in clouds that resulted in electrostatic charging and slight luminescence of certain material.

Ben Franklin was known for his early experiments with electrical charges.
Ben Franklin was known for his early experiments with electrical charges.

Friction between air and cloud particles creates electrostatic charge buildup in clouds. The voltages generated in clouds at elevated altitudes can reach far beyond billions of volts. When the atmospheric conditions build a lower-resistance path between the charged cloud and the ground, lightning strikes where most of the energy reaches the ground. The high current associated with a lightning strike is conducted to the ground by an ionized section of the atmosphere, and this can easily induce voltages in conductive material such as steel towers and electrical cabling. The result is current-induced voltage that may damage sensitive electronic equipment.

Lightning can induce voltages in conductive materials.
Lightning can induce voltages in conductive materials.

Field-induced voltage is created by either an electric or magnetic field. A voltage-induced electric field is when a capacitor or condenser is charged with a direct current and a positive charge on one plate and a negative charge on the other plate are induced. The same capacitor will have a voltage across its terminals, and this is field-induced voltage. In voltage alteration, the resulting current flow changes voltage level. When lightning discharges a cloud formation, the extremely high voltage that has previously caused the lightning decreases to a certain level determined by air and ground conditions.

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This voltage may further create a magnetic field, thus it may be referred to as an induced voltage magnetic field. When lightning hits the lightning arrestor on top of a radio tower, the current surge travels toward the ground on the grounding cable. This current generates a transient magnetic field that may induce a voltage on any nearby conductor. The transformation may recur as extensively as the intensity of the original energy allows. This may suggest why the damage to equipment due to current and voltage surges during lightning storms can be extensive.

In an electrical transformer, the primary winding induces a voltage across the secondary winding. The induced voltage formula suggests that the ratio of the output to input voltage is equal to the ratio of the number or turns on primary to that of the secondary winding. Additionally, the voltage test on a transformer uses a voltmeter connected to the input terminals and later to the output terminals of the transformer. By comparing the two readings, it is possible to calculate the ratio of turns.

The voltages generated in clouds at elevated altitudes can reach far beyond billions of volts.
The voltages generated in clouds at elevated altitudes can reach far beyond billions of volts.

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Discussion Comments


Scientists would love to find a way to harvest lightning and other natural energies. The hardest part of storage is leakage. You have all this energy in one container and there will always be some that leaks out.

The main way we store energy now is in batteries. Technology in batteries is getting better every year. Someday scientists hope to make a nearly perfect battery with as little leakage as possible.


When you have a large build up of energy in a cloud and it reaches a critical level the energy jumps to the ground in a magnificent flash. This is what we call lightning. The amazing thing about lightning is that the sound it makes is really made by air. When the bolt of lightning rips through the air, it leaves a gap in the air. When this gap is quickly filled again with air, that is when you get the loud clap sound.

A bolt of lightning typically has a billion volts in one strike. There have been bolts that measured as high as 6 billion volts.

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