Basic Components

Batteries

A battery is a device that stores chemical energy and converts it to electrical energy.

A battery is a source of energy which provides a push – a voltage – of energy to get the current flowing in a circuit. A bulb uses the electrical energy provided by the battery, but does not use current. When the energy in the battery is used up there is no current and the bulb does not light up.

Resistor

The resistor is a passive electrical component to create resistance in the flow of electric current. In almost all electrical networks and electronic circuits they can be found. The resistance is measured in ohms. An ohm is the resistance that occurs when a current of one ampere passes through a resistor with a one volt drop across its terminals. This ratio is  represented by Ohm’s law:

formula with ohm's law: R=V/I

Resistors are used for many purposes. A few examples include delimit electric current, voltage division, heat generation, matching and loading circuits, control gain, and fix time constants.

Resistor Color Coding uses colored bands to quickly identify a resistors resistive value and its percentage of tolerance with the physical size of the resistor indicating its wattage rating. 

Generally, the resistance value, tolerance, and wattage rating are printed on the body of a resistor as numbers or letters when the resistors body is big enough to read the print.

Example:

A resistor colored Yellow-Violet-Orange-Gold would be 47 kΩ with a tolerance of +/- 5%.

Capacitor

A capacitor is a device that stores electrical energy in an electric field. It is a passive electronic component with two terminals. The effect of a capacitor is known as capacitance.

Capacitance is expressed as the ratio of the electric charge on each conductor to the potential difference (i.e., voltage) between them.

The capacitance value of a capacitor is measured in farads (F),

LED

LED stands for Light-Emitting Diode. It’s a type of diode that emits light when it has a current flowing through itself.

It is commonly used for showing a state of the electronics. For example to show that the circuit is powered.

Connecting a LED:

The LED has two pins called anode and cathode. The anode is the longest pin. This is the pin you connect to the most positive voltage. The cathode is the pin you connect to the most negative voltage. They must be connected correctly for the LED to work.

An LED always has a resistor in series with it.

If you run too much current through an LED, it will get really hot and break down. That’s why the resistor is there – to control how much current that goes through the LED. We call this a current limiting resistor.