Physics - Electricity and Simple Circuits

Electric charge ($Q$) is measured in Coulombs ($C$). It can be positive or negative; like charges repel and opposite charges attract.

Electric current ($I$) is defined as the rate of flow of electric charge. It is measured in Amperes ($A$) using an ammeter connected in series.

Potential Difference ($V$), or voltage, is the work done (energy transferred) per unit charge. It is measured in Volts ($V$) using a voltmeter connected in parallel.

Resistance ($R$) is the property of a component that opposes the flow of current, measured in Ohms ($\Omega$).

In a series circuit, there is only one path for the current. The current $I$ is the same at all points, but the total voltage $V_{total}$ is shared between components.

In a parallel circuit, there are multiple branches. The voltage $V$ is the same across each branch, but the total current $I_{total}$ is the sum of the currents in each branch.

Conductors (like copper) allow electrons to flow easily, whereas insulators (like plastic) have a very high resistance and prevent the flow of charge.