#### • Class 11 Physics Demo

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# 1 Coulomb Equals

Coulomb is a basic unit of electrical charge and also coulomb is the SI unit of electric charge. Its unit symbol is ‘C’.

1 – coulomb – equals the charge of 6.241 × 1018 electrons approximately.
Also 1 – coulomb – equals the product of one ampere in one sec. We can also say that 1 – coulomb – equals the amounts of excessive charge that is on the positive side of a capacitor of a farad that is charged to a potential difference of a volt.
It was named after the scientist Charles–Augustin de Coulomb.

Generally the coulomb is defined in amperes and seconds: 1 C = 1 A × 1 s. Seconds can be defined as the frequency that is emitted by the caesium atoms naturally and the ampere can be defined with the use of Ampere’s force law. Practically, we use the watt balance for measuring amperes that too with the maximum accuracy level possible.

Now, the charge of an electron is about 1.60217657 × 10-19 coulombs. So by taking the reciprocal of the same also, 1 – coulomb – equals or can be considered to be 6.241509324 × 1018 electrons or protons.

Below are given some of the conversions:
• The Faraday unit of charge is the value of the electrical charge of one mole and the value of one Faraday is 96485.3399 coulombs.
• The value of 1 ampere hour is 3600 coulombs.
• The basic charge is equal to 1.602176487 × 10-19 coulombs.
• The value of obsolete electrostatic charge unit in CGS is 3.3356 × 10-10 coulombs approximately. This is one third of a nano-coulomb.
• The magnitude of the electrical charge in 6.24150965 (16) × 1018 protons or electrons is the value of one coulomb.
Various examples of coulomb charge in daily life are stated below:
• The charges in the static electricity generated from rubbing of the materials together with each other of measure of a few micro-coulombs.
• The measure of charge that is travelling through a lightning bolt is somewhere around 15 coulombs. It is also a fact that large bolts can be of measure up to 350 coulombs.
• The amount of the charge which is travelling through a normal alkaline battery of AA standard is near to 5 kC which is equal to 5000 coulombs that is nearly equal to 1.4 A-h. After this much charge has been flowed, wither the battery should be discarded or it should be recharged.
• The Coulomb’s law states that, when two negative point of charges of 1 coulomb each are placed one meter apart, a repulsive force of 9 × 109 N is experienced.
• The hydraulic analogy equates the charge to a given volume of the water and the voltage to the pressure. The measure of one coulomb is the value of negative charge of 6.24 × 1018 electrons. The energy amount that is transferring in the flow of one coulomb might vary. This can be seen by the comparison here: in comparison to a dry cell battery, 300 times lesser electrons flow through a lightning bolt while the total energy that is transferring with the flow of the electrons in a lightning is greater 300 million times.