Power

Our Android Things creations are going to need power to operate, so it’s important to understand the concepts surrounding this. Our source of power (such as a power supply or similar means of electricity) is going to provide us with voltage that can be used to power our board and components that are connected to it.

But what is voltage? Well, it’s technical description states that is is the “difference in charge between two points in an electrical field” . A simpler way of looking at it is pressure, it is the force pushing electrons through our circuit. This value has a direct effect on the current of our circuit too, as the higher the voltage in our circuit the faster electrons will flow. And sometimes, we may want to reduce that flow of current through our circuit — this can be done by applying resistance to our circuit.

With voltage (V), current (I) and resistance (R) — that’s where OHMs law comes in to play. This law simply states that “electric current is proportional to voltage and inversely proportional to resistance”, meaning that we can use it to calculate one of the V / I / R values based off of the other two. This is useful as for example, if you know both the voltage and current of your circuit then you can use these values to easily calculate the resistance required for your circuit. The law states that we can calculate these values like so:

Voltage = Current * Resistance

= Current * Resistance Current = Voltage / Resistance

= Voltage / Resistance Resistance = Voltage / Current

This formulas can be easily remembered by using this visual representation: