Fundamental Principles of Electric Circuits and Materials

Properties of Metals and Non-Metals

Non-Metals

• They have many electrons in the outer shell.
• Atoms want to be stable with the outer shell complete.
• Non-metals gain electrons.
• Non-metals do not let electrons flow (no electricity).

Metals

• They have many electrons in the outer shells.
• The atoms want to be stable with the outer shell complete.
• Metals lose electrons.
• Metals let electrons flow (electricity).

Components of an Electric Circuit

An electric circuit is the pathway for the flow of electrons. It consists of:

1. Generator: It is the element that provides the energy that electrons need to move. It obtains energy through technical processes.
2. Wire: It connects all the elements of a circuit. It is made of copper.
3. Loads or Receptors: They transform electrical energy into other types of energy that we can use. There are four types:
   • Light bulbs: They transform electrical energy into light.
   • Motors: They transform electrical energy into movement.
   • Resistors: They transform electrical energy into heat.
   • Bells: They transform electrical energy into sound.
4. Switches: They allow or interrupt the flow of electrons. It is not necessary to keep the switches pushed to let electrons flow.
5. Push Buttons: They allow or interrupt the flow of electrons. It is necessary to keep the buttons pushed to let the electrons flow.
6. Fuses (Fusibles): They protect the circuit against high electric currents. They prevent the loads from being broken.

Diagrams and Symbols

We use conventional symbols to simplify the visual representation of electric and electronic circuits.

Electrical Quantities and Formulas

1. Voltage: It is the amount of energy that the generator can transfer to electrons. It is measured in Volts (V).
2. Electric Current: It is the number of electron charges that flow through the circuit per second. It is measured in Amperes (A). We express this mathematically as follows: I = Q / T.
3. Resistance: It is the opposition of a material to the flow of electrons. It is measured in Ohms (Ω). Formula: V = I · R.
4. Electric Energy: It is measured in Joules (J). Formula: E = V · I · T.
5. Electric Power: It is measured in Watts (W). Formula: P = V · I.