Physics: Electricity and Magnetism - Static Electricity and Electric and Magnetic Fields

Electric Charge: Matter is made of atoms containing protons (positive charge, $+e$) and electrons (negative charge, $-e$). The SI unit for charge ($Q$) is the Coulomb ($C$).

Law of Electrostatics: Like charges repel each other, while opposite charges attract each other ($+ \leftrightarrow +$ and $+ \rightarrow \leftarrow -$).

Charging by Friction: When two different insulators are rubbed together, electrons are transferred from one to the other. The object that loses electrons becomes positively charged, and the one that gains electrons becomes negatively charged ($Q = n \times e$).

Electric Fields: An electric field is a region around a charged particle where a force would be exerted on other charges. Field lines always point away from positive charges ($+$) and towards negative charges ($-$).

Magnetic Poles: Every magnet has two poles: North ($N$) and South ($S$). Like poles repel, and opposite poles attract.

Magnetic Fields: The region around a magnet where magnetic forces can be detected. Field lines emerge from the North pole and enter the South pole.

Electromagnetism: An electric current ($I$) flowing through a conductor creates a magnetic field. The strength of an electromagnet can be increased by increasing the current ($I$), increasing the number of turns in the coil ($N$), or adding a ferromagnetic core (like iron).