We all want to do something big when we start learn something, but before making big thing we need to begin with the initial knowledge because before running we need to be able to walk.
Same like this we need basic circuitry information before to make many more great things. In this will we see how to use different electronic components in a circuit and what is the use of them. Here we begin with power source.
Here we can see two DC power source, one is a battery of 5V which has two terminals positive and negative & in other diagram we see one terminal as power of +5V and other is ground, so that potential difference across them becomes 5V and works same as battery.
So in these tutorials you will see sometimes battery symbol and sometimes power and ground.
All power & ground symbol in a circuit are suppose to same source (Suppose in a circuit I need two +5V, for this I have two choices to show either connect a wire or placed another power of same +5V).
ACTIVE AND PASSIVE COMPONENTS
According to wikipedia
Active components rely on a source of energy (usually from the DC circuit, which we choose to ignore) and usually can inject power into a circuit, though this is not part of the definition.
Examples of active components include amplifying components such as transistors, triode vacuum tubes (valves), and tunnel diodes.
Passive components can’t introduce net energy into the circuit. They also can’t rely on a source of power, except for what is available from the (AC) circuit they are connected to.
As a consequence they can’t amplify (increase the power of a signal), although they may increase a voltage or current (such as is done by a transformer or resonant circuit).
Examples of passive components include two-terminal components such as resistors, capacitors, inductors, and transformers.