**Charge, voltage, current and resistance**

**Charge** can be positive or negative, where the electron has a negative charge while the proton has a positive charge. Charge is measured in Coulombs. opposite charges attract each other while similar charges repel.**Voltage** is the difference in charge between two points. Voltage is measured in Volts.**Current** is the rate at which charge is flowing. Current is measured in Amperes**Resistance** is a material's tendency to resist the flow of charge (current). Resistance is measured Ohm.

**Ohm's law**

**Ohm's law** states that the current through a conductor between two points is directly proportional to the voltage across the two points.

The constant of proportionality is called the resistance, *R*.

Ohm’s law is given as follows:

V = I R

Where *I* is the current through the conductor in units of amperes, *V* is the voltage measured *across* the conductor in units of volts, and *R* is the resistance of the conductor in units of ohms.

**Kirchhoff’s Law**

**Kirchhoff** described 2 laws as follows:-

1. **Kirchhoff’s Current Law **(**KCL**):- This law is also called Kirchhoff's first law, Kirchhoff's point rule, or Kirchhoff's junction rule (or nodal rule).

This law states that, for any node (junction) in an electrical circuit, the sum of currents flowing into that node is equal to the sum of currents flowing out of that node.

or equivalently:

**The algebraic sum of currents in a network of conductors meeting at a point is zero**.

2. **Kirchhoff’s Voltage Law **(**KVL**): This law is also called **Kirchhoff's second law**, **Kirchhoff's loop** (or **mesh**) **rule**, and **Kirchhoff's second rule**.

This law states that:

** The directed sum of the potential differences (voltages) around any closed loop is zero.**