Voltage and Charge

Charge and Current

Charge is a property of matter carried by certain subatomic particles, such as electrons and protons, which affects their electromagnetic interactions.
Electric charge comes in two types, negative (carried by electrons) and positive (carried by protons).
The unit of charge is the coulomb (C).
Electric current is the flow of electric charge. It is measured in amperes (A).
The direction of current is taken as the direction in which positive charges would flow.

Coulomb’s Law describes the force between two charged particles. The force is directly proportional to the product of the magnitudes of their charges and inversely proportional to the square of the distance between their centres.
The law can be represented by the formula F = k(q1*q2)/r^2, where F is the force between the charges, q1 and q2 are the charges, r is the distance between the charges, and k is Coulomb’s constant.

Direct Current (DC) flows in one direction, and is generated by cells and batteries.
Alternating Current (AC) changes direction at a regular interval, and is generated in all power stations.
The net charge flow in a closed circuit is zero; this is known as Kirchhoff’s first law or the principle of conservation of charge.

Voltage (also known as potential difference) is the work done per unit charge. It is measured in volts (V).
The formula for voltage is V = W/Q, where V is the voltage, W is the work done or energy transferred, and Q is the charge.
The amount of charge that flows in a circuit depends on the voltage and resistance.
The higher the voltage, the more charge will flow. The higher the resistance, the less charge will flow.

A capacitor is a component that can store charge.
The amount of charge held by a capacitor is directly proportional to the voltage across it. This relationship can be expressed with the formula Q = CV, where Q is charge, C is capacitance, and V is voltage.