Electric Charge Converter
Convert Coulombs (C), elementary charge (e), Ampere-hour (Ah), Faraday (F), statcoulomb, abcoulomb.
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*Diagram shows values relative to the selected base unit (Coulomb).
Unit Information
What is a Coulomb (C)?
The Coulomb (symbol: C) is the SI derived unit of electric charge. It is defined as the amount of electric charge transported by a constant current of one ampere in one second (1 C = 1 A·s). The Coulomb is named after Charles-Augustin de Coulomb, a French physicist known for his work on electrostatics.
What are Millicoulombs, Microcoulombs, Nanocoulombs, and Picocoulombs?
These are standard SI submultiples of the Coulomb. Millicoulomb (mC) is 10⁻³ C. Microcoulomb (µC) is 10⁻⁶ C. Nanocoulomb (nC) is 10⁻⁹ C. Picocoulomb (pC) is 10⁻¹² C. These smaller units are used in electrostatics, sensor design, and particle physics where the charge quantities are very small.
What is an Ampere-hour (Ah)?
An Ampere-hour (symbol: Ah or A·h) is a unit of electric charge, commonly used to measure the capacity of batteries. One ampere-hour is the charge transferred by a steady current of one ampere flowing for one hour, which is equivalent to 3600 coulombs.
What is a Milliampere-hour (mAh)?
A milliampere-hour is one-thousandth of an Ampere-hour (1 Ah = 1000 mAh). It is the most common unit for specifying the capacity of smaller batteries, such as those in smartphones, laptops, and other consumer electronics.
What is Elementary Charge (e)?
The elementary charge (symbol: e) is the smallest discrete unit of electric charge observed in nature (for free particles). It's the magnitude of the charge of a single proton (+e) or a single electron (-e). It is approximately 1.602 × 10⁻¹⁹ Coulombs. All observable charge is an integer multiple of this value.
What is a Faraday (chemical)?
A Faraday is a unit of charge equal to the total charge of one mole of elementary charges (e.g., electrons). It is named after Michael Faraday. The Faraday constant (F) is approximately 96,485 coulombs per mole. It is used extensively in electrochemistry.
What is a Statcoulomb (statC or esu)?
The statcoulomb (or Franklin) is the CGS-ESU (electrostatic) unit of charge. It is defined as the charge such that two objects with a charge of 1 statC each, placed 1 cm apart, will repel each other with a force of 1 dyne. It is a very small unit of charge.
What is an Abcoulomb (abC or emu)?
The abcoulomb is the CGS-EMU (electromagnetic) unit of charge. It is a larger unit, defined as exactly 10 Coulombs. It is derived from the definition of the abampere and is rarely used today.
Formulas
1 Ah = 3600 C
One Ampere-hour is equal to 3600 Coulombs (1 Ampere × 3600 seconds).
1 e ≈ 1.602 × 10⁻¹⁹ C
One elementary charge is approximately 1.602 × 10⁻¹⁹ Coulombs.
1 Faraday ≈ 96485 C/mol
The Faraday constant is approximately 96,485 Coulombs per mole of electrons.
Q = I × t
Charge (Q) in Coulombs equals Current (I) in Amperes multiplied by time (t) in seconds.
Q = C × V
Charge (Q) stored on a capacitor equals its Capacitance (C) in Farads multiplied by the Voltage (V) across it.
Key Reference Points
- Charge of a single electron: -1.602 × 10⁻¹⁹ Coulombs (-e).
- A typical AA battery might store ~2000-2500 mAh (7200-9000 Coulombs).
- A car battery capacity: ~40-70 Ah (144,000-252,000 Coulombs).
- A typical lightning bolt can transfer 5 to 50 Coulombs of charge.
- Charge to electrolyze one mole of water: Approx. 193,000 Coulombs (2 Faradays).
- Charge on a capacitor in a typical electronic circuit: Microcoulombs (µC) to millicoulombs (mC).
- Charge transferred by a static shock from a doorknob: Can be in the range of 1-10 microcoulombs (µC).
- Charge of a single alpha particle (Helium nucleus): +2 e.
- A single ion in a solution carries a charge of a few elementary charges.
- Charge sensitivity of some modern transistors can be in the range of single electrons.
Did You Know?
Benjamin Franklin's experiments with electricity, particularly his famous kite experiment, contributed significantly to the understanding of electric charge. He proposed the convention of positive and negative charges, where rubbing glass with silk was considered to produce 'positive' charge on the glass. We now know this corresponds to a deficiency of electrons.
The law of conservation of electric charge is a fundamental principle stating that the total electric charge in an isolated system remains constant. Charge cannot be created or destroyed, only transferred from one object to another.
Static electricity, like the shock you get from a doorknob after walking on carpet, is due to an imbalance of electric charges on the surface of objects. The transfer of electrons creates this imbalance.
In 1909, Robert Millikan performed his famous oil drop experiment, which allowed him to measure the charge of a single electron (the elementary charge, 'e') with great precision for the first time.
This is the effect that causes static electricity when certain materials are rubbed together, like a balloon on hair. Materials are ranked in a 'triboelectric series' to predict which will become positively or negatively charged when rubbed against another.
A Faraday cage is an enclosure made of a conductive material that blocks external static and non-static electric fields. It works because the electric field causes the charges in the conductor to redistribute and cancel the field's effect inside the cage.
Plasma is a state of matter where atoms are ionized, meaning they've been stripped of some or all of their electrons. This results in a 'soup' of positively charged ions and negatively charged electrons. Stars, lightning, and the aurora are all examples of plasma.
A typical lightning bolt can transfer a massive amount of charge, ranging from 5 to 50 Coulombs, in a fraction of a second, with currents reaching tens of thousands of amperes.
A fundamental principle of physics is that electric charge is 'quantized,' meaning it only exists in discrete multiples of the elementary charge (e). You can have a charge of 2e or -3e, but not 1.5e (except for quarks).
This is a laboratory technique that uses an electric field to separate charged molecules like DNA, RNA, and proteins. The molecules move through a gel at different speeds depending on their size and charge.
The electron-volt is a unit of energy, but it's defined by charge. It's the amount of kinetic energy gained by a single electron when accelerated through an electric potential difference of one volt.
A capacitor is an electronic component that stores electric charge. The amount of charge (Q) it can store is equal to its capacitance (C) multiplied by the voltage (V) across it (Q = CV).
In industrial processes like the refining of copper, a large electric charge is passed through a solution. This causes pure copper ions to deposit onto the cathode, leaving impurities behind and resulting in very high-purity metal.
A typical lightning bolt transfers about 5 Coulombs of charge. This is equivalent to more than 30 quintillion (3 x 10¹⁹) electrons moving from the cloud to the ground.
Coulomb's Law describes the electrostatic force between two charged particles. The force is proportional to the product of the charges and inversely proportional to the square of the distance between them, similar in form to Newton's Law of Universal Gravitation.
Charge density describes how much electric charge is accumulated in a particular area or volume. In electronics, controlling charge density is key to how components like transistors and capacitors function.
The piezoelectric effect is the ability of certain materials (like quartz crystals) to generate an electric charge in response to applied mechanical stress. This is used in applications like gas grill lighters and pressure sensors.
The abcoulomb is the CGS-EMU (electromagnetic) unit of charge. One abcoulomb is equal to ten Coulombs. It is based on the force between two parallel current-carrying wires and is rarely used today.