UNIT 1: ELECTRICITY AND ELECTRONICS (PART 1) TECHNOLOGIES ESO 3

ELECTRICITY AND ELECTRONICS 1.ATOMS 2.ELECTRIC CIRCUITS 2.1 ELECTRIC CURRENT AND ELECTRIC CIRCUITS 2.2 COMPONENTS OF AN ELECTRIC CIRCUIT 2.3 REPRESENTATION AND SYMBOLS 3.ELECTRIC MAGNITUDES 3.1 VOLTAGE 3.2 CURRENT 3.3 RESISTANCE 3.4 OHM´S LAW

1. ATOMS Atoms are the tiny particles that make up all matter. Every atom has a central core called a “NUCLEUS”, the nucleus contains the two heaviest nuclear particles ________ and __________ __________circle around the nucleus, with different groups circling in different layers, or shells. PROTONSNEUTRONS. ELECTRONS

2. ELECTRIC CIRCUITS 2.1. ELECTRIC CURRENT AND ELECTRIC CIRCUITS Electric current is the flow of electrons around a circuit. Electrons have to “scape” from the nucleus of the atom to flow, the electrical conductivity depends on the atomic structure of material. Pay attention to these atoms: What are the differences in the atomic structure of this elements ?

2. ELECTRIC CIRCUITS 2.1. ELECTRIC CURRENT AND ELECTRIC CIRCUITS Electric circuit is a close path around which electrons can move. A circuit is a group of components connected together to do a specific job. ____________ allow electric currents to pass through them. All metals belong to this group: copper, iron, silver… ___________don’t allow electric currents to pass through them. Plastic, wood and glass are examples of this group. _________________ have properties which are intermediate between previous groups. The most important examples are silicon and germanium. ELECTRICAL PROPERTIES OF MATERIALS: CONDUCTORS INSULATORS SEMI-CONDUCTORS

Generators provide the energy for electrons to circulate. The power for many electrics an electronics circuits comes from batteries. A battery stores electric energy and, when connected to a circuit, it provides the force to the electrons to run along the wires. A. GENERATORS Dynamos and alternators are used for large scale power generation and industry. 2. ELECTRIC CIRCUITS 2.2. COMPONENTS OF AN ELECTRICAL CIRCUIT

They transform electrical energy into another form of energy. For example, light bulbs, lamps or LEDs transform electrical energy into light, motors transform electrical energy into movement, buzzers transform electrical energy into sound. B. RECEIVERS 2. ELECTRIC CIRCUITS 2.2. COMPONENTS OF AN ELECTRICAL CIRCUIT

These are elements used to control the flow of electrons through the circuit. Switches are mechanical devices that can make (connect), break (disconnect) a circuit or divert the current from one conductor to another (circuit switch or crossover switch). A push botton allows the current to flow only when pressure is mantained. C. CONTROL ELEMENTS 2. ELECTRIC CIRCUITS 2.2. COMPONENTS OF AN ELECTRICAL CIRCUIT

These are elements used to protect the circuit against excessive current, voltage or current leakage. The most important elements in this group are fuses (that cuts the circuit by melting when the current is too high), breaker switches (automatic fuses) and differential switches (than protect against current leakage). D. PROTECTION ELEMENTS 2. ELECTRIC CIRCUITS 2.2. COMPONENTS OF AN ELECTRICAL CIRCUIT

BATTERIES: LIGHT BULB/LAMP: MOTOR: BUZZER/BELL: LED: SWITCH: PUSH BUTTON: CIRCUIT SWITCH: RESISTORS: 2. ELECTRIC CIRCUITS 2.3. REPRESENTATION AND SYMBOLS

3. ELECTRIC MAGNITUDES (Also called potential difference and tension) Definition: Voltage or tension is the energy that a battery or generator can provide for each electron. Unit: volts (V) Measure: voltmeter 3.1 VOLTAGE 3.2 ELECTRIC CURRENT Definition: Electric current is the charge, or number of electrons, that flows through a conductor per second. I = Q/t Q= electric charge, measured in coulombs (C). 1 C = 6.25 ·10 18 electrons Unit: amperes o amps (A) Measure: ammeter

3. ELECTRIC MAGNITUDES 3.3 RESISTANCE Definition: Resistance is a measure of how easily (or with what difficulty) electrons will flow through the device. Copper wire has a very low resistance, so a small voltage will allow a large current to flow. Likewise, the plastic insulation has a very high resistance, and prevents current from flowing from one wire to those adjacent. Units: ohms, Ω 3.4 OHM´S LAW Voltage, current and resistance are quantities related. Current flowing through a circuit is increased in relation to the voltage and may also change depending on the material used. Ohm’s law expresses these relations as follows: I = V/R