# Current and Resistance

## Key Questions

$V = I \cdot R$ or other forms...

#### Explanation:

Ohm's law describes the relationship between voltage, current and resistance.

It can be expressed in the form: $V = I \cdot R$ where $V$ is the voltage (measured in volts), $I$ the current (measured in amperes) and $R$ the resistance (measured in ohms).

This is also expressible in the VIR triangle:

$V = I \cdot R$

$I = \frac{V}{R}$

$R = \frac{V}{I}$

• A thicker wire (of the same material) has lower resistance.

Having a thicker wire means that the volume of conducting material has increased so there are more conduction electrons available.

A concrete example of this point would be consider the current that flows through a wire. Now take a second identical wire and set it parallel with the first. The current that flows through the parallel combination would be larger (by a factor of two). Therefore the resistance of that arrangement must be less than the single wire (half the resistance of the single wire).