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System of Units

The International System of Units (SI units) are rules for units

  • T, Tera: 1012=1,000,000,000,00010^{12} = 1,000,000,000,000
  • G, Giga: 109=1,000,000,00010^{9} = 1,000,000,000
  • M, Mega: 106=1,000,00010^{6} = 1,000,000
  • K, Kilo: 103=1,00010^{3} = 1,000
  • m, Mili: 103=0.00110^{-3} = 0.001
  • μ, Micro: 106=0.000,00110^{-6} = 0.000,001
  • n, Nano: 109=0.000,000,00110^{-9} = 0.000,000,001
  • p, Pico: 1012=0.000,000,000,00110^{-12} = 0.000,000,000,001

Voltage (V)

Volts are like water pressure for electricity.

The height of water viewed from a given reference point is called the water level. Electricity also has a comparable concept called potential difference, measured in V.

Voltage is the difference in potential between 2 points. Think of electricity as water.

Ampere (A)

An Amp or Ampere, A, is the unit representing the electric current I — the amount of electricty flowing per secod through an electric line — think of it as water volume per second.

One amp is equal to one coulomb per second.

Watt (W)

A Watt, W, is the consumed electric power.


Power (W)= Voltage (V) Current (I)\text{Power }(W) = \text{ Voltage } (V) \cdot \text{ Current } (I)

And we can rearrange this to find the current I by dividing V from the right side and doing the same to the left — algebra mofo!

 Current (I)=Power (W) Voltage (V)\text{ Current } (I) = \dfrac{\text{Power }(W)}{ \text{ Voltage } (V)}


When external heat or light is added to an atom an electron may escape from the atom, called a free electron, causing atom to become electrically positive (bc 4 : 3 becomes 3 : 3). This escaped electron will move to another atom.


Charge creates a repels or attracts. When the ratio of protons to electrons is equal then they attract. If the ratio is broken then the electron repels, becoming a free electron, to bring the atom back to equilibrium. Atoms are always trying to become neutral by losing or receiving electrons.

This force is called the electrostatic force, aka coulomb’s force.

Static electricity occurs when a material has a positive or negative electric charge that is not moving.

Current (I)

Current is the quantity of electricity flowing per second through an electric line, and it is represented using the symbol I, which comes from the initial letter of Intensity of electricity.

Electrons move opposite to the direction of the current.


Objects which electricty can easily flow through, like copper.


Objects which electricity has difficulty flowing through, e.g. rubber or glass. This is why copper wiring is wrapped around rubber!

if there is an insulator between a positive and a negative charge, the electrons cannot move.


These are the midway between insulators and conductors.

Electrical Discharge

If objects having charge are connected by a conductor like copper wire the negative electrons move to the positive side. Then, the positives and negatives unite to cancel each other out, and te charged state no longer exists. This called electrical discharge — which can also occur in the air or in a vacuum, e.g. lightning!

Static Electricity

Static electricity means nothing is moving — no current flows! It is more easily generated when the air is dry — like in winter, when the humidity level is low

Air purifiers work because fine dust (negatively charged) is attracted to the filter (positively charged). And printers work bc we positively charge the parts we want to print and negatively charging the ink the machine can print copies just the way you want them. Since the same charge repel each other the negatively charged areas do not print while the positive areas attract the negatively charged ink.

Electrostatic Induction

Static shock is when the positive and negate charges are being exchanged. If something that is not charged approaches something that is charged it becomes charged too.