OHM'S LAW

THE FIRST STEP 

UNDERSTANDING THE CIRCUIT

So back again let's start the journey of our programming sessions,,, First of all, some prerequisites such as some basic knowledge of C and some simple Ohm's Law.

YOU’LL MAKE A SIMPLE CIRCUIT WITH SOME SWITCHES, AN LED, AND A RESISTOR.

Electricity is a type of energy, much like heat, gravity, or light. Electrical energy flows through conductors, like wire. You can convert electrical energy into other forms of energy to do something interesting, like turn on a light or make some the noise out of a speaker.

The components you might use to do this, like speakers or light bulbs, are electrical transducers. Transducers change other types of energy into electrical energy and vice versa. Things that convert other forms of energy into electrical energy are often called sensors, and things that convert electrical energy into other forms of energy are sometimes called actuators. You will be building circuits to move electricity through different components. Circuits are closed loops of wire with a power source (like a battery) and something to do something useful with the energy, called a load.

 In a circuit, electricity flows from a point of higher potential energy (usually referred to as power or +) to a point of lower potential energy. Ground (often represented with a - or GND) is generally the point of least potential energy in a circuit. In the circuits you are building, electricity only flows in one direction. This type of circuit is called direct current, or DC. In alternating current (AC) circuits electricity changes its direction 50 or 60 times a second (depending on where you live). This is the type of electricity that comes from a wall socket.

There are a few terms you should be familiar with when working with electrical circuits. Current (measured in amperes, or amps; with the A symbol) is the amount of electrical charge flowing past a specific point in your circuit. Voltage (measured in volts; with the V symbol) is the difference in energy between one point in a circuit and another. And finally, resistance (measured in ohms; with the Ω symbol) is how much a component resists the flow of electrical energy.

Your first interactive circuit, using a switch, a resistor, and an LED. Arduino is just the power source for this circuit; in later projects, you'll connect its input and output pins to control more complex circuits.

Current, voltage and resistance are all related. When you change one of these in a circuit, it affects the others. The relationship between them is known as Ohm's Law, named for Georg Simon Ohm, who discovered it. 

VOLTAGE (V) = CURRENT (I) * RESISTANCE (R)