The electrons are always there, for example in the metal. You don't need a special "source" for electrons in a circuit. What you DO need is a voltage source, i.e., something that pushes the electrons around.
The part of an electric circuit that adds electric energy is called a "source." Common examples of sources include batteries and power supplies, which convert stored energy or electrical energy from the grid into a usable form for the circuit. These sources provide the necessary voltage and current to drive the operation of electrical devices and components within the circuit.
The main purpose of a source in an electric circuit is to provide electrical energy, typically in the form of voltage, which drives the flow of electric current. This energy allows electrical devices and components within the circuit to operate and perform their intended functions. Common examples of sources include batteries, generators, and power supplies.
You need a source of electrical potential difference, also known as voltage (which is the technical term for what for you call "electric pressure"). The easiest and most common voltage source is a household battery. Hook up the positive electrode of the battery using a conductor (eg. a copper wire) to one end of your circuit and the negative electrode to the other end, and voila, you'll have electric current flowing through your circuit.
If the energy meter is connected in the common outlet circuit, it would record the energy flow from both the sources. If you want to record the energy from two different sources separately, then you need to provide two different meters in each circuit.
Transistor, resistor, diode, output.
An electric circuit is a closed loop that allows a flow of electrons to begin from a source of the electrons and return to the same source. Some of the energy carried by the current from the source may or may not be released to perform useful work. Because of the resistance of the materials in the circuit, some of the energy carried by the current is always lost as heat emitted from the circuit into the surrounding environment. The flow of electrons around the closed loop is called an electric current. The source of the electrons must be a chemical battery or a mechanical generator which produces a potential difference, also known as a voltage.
In common practice, the principle reservoir for electric charge is a battery. Fuel cells, which are like batteries except with external reactant sources, are becoming more widely used as electric reservoirs. In pure circuit design, the capacitor is used as the charge reservoir.
in an electric circuit, it is treated as a reference from which other voltages can be measured. also it acts as a common return path of electric current leakages
Electric current is typically measured in amperes (A), which represent the rate at which electric charge is flowing through a circuit. Other common units for measuring electric current include milliamperes (mA) and microamperes (µA).
The device is called a switch.
Electric current is a flow of electric change through a medium can also be carried by ions is an electrolyte by both ions and electrons in a plasma to their Lower Masses electrons in a plasma accelerate more quickly in response.
Natural light sources and artificial sources emit light with orientations of the electric vector that are random in space and time, thus proving to be nonpolarized.