ELECTRIC CIRCUITS AND ELECTRONICS

Transcription

1 Circuitos eléctricos y electrónicos ELECTRIC CIRCUITS AND ELECTRONICS Technology, programming and robotics II

2 Electric Circuitos circuits eléctricos and y electronics electrónicos AN ELECTRICAL CIRCUIT Oxford University Press España, S. A. Technology, programming and robotics II 2

3 Circuitos eléctricos y electrónicos Electric circuits and electronics An electric circuit is a pathaway for the flow of electrons. Electrons have negative charge and are continually in motion Oxford University Press España, S. A. Technology, programming and robotics II 3

4 1. Electricity: Fundamental concepts GENERATORS: To produce the flow of electrons, there must be a source of energy. This source of energy is normally a battery. Normally, electric current is generated by chemical processes.

5 1. Electricity: Fundamental concepts Load (receptor): transforms electricity into another type of energy: Light Heat Motion

6 1. Electricity: Fundamental concepts Switching devices: are used to direct and interrupt the flow of electric current. Switches: on or off Push buttons: circuit will work while they are pushed 3-way switches: permit the flow through one path while stopping another

7 1. Electricity: Fundamental concepts Connectors: The parts that we have seen are connected by wires made of copper principally. These wires are covered with insulating materials

8 1. Electricity: Fundamental concepts In electronics, there are 3 types of materials that we can use: Conductors: they always conduct the electricity, no matter what. Examples: Copper or alumminum Semiconductors: They conduct the electricity depending on some variables (temperature, magnetism, etc). Examples: Silicon or germanium Insulating: they cannot conduct electricity. Examples: wood or glass

9 Electric Circuitos circuits eléctricos and y electronics electrónicos PARTS OF AN ELECTRIC CIRCUIT Oxford University Press España, S. A. Technology, programming and robotics II 9

10 Circuitos eléctricos y electrónicos Electric circuits and electronics Symbols: Battery Light bulb Resistor Motor Bell Push button 3-way switch Fuse Ammeter Voltmeter Switch Oxford University Press España, S. A. Technology, programming and robotics II 1

11 Electric Circuitos circuits eléctricos and y electronics electrónicos ELECTRICAL RESISTANCE: OHM'S LAW Oxford University Press España, S. A. Technology, programming and robotics II 11

12 Electric Circuitos circuits eléctricos and y electronics electrónicos The voltage (V) is the amount of energy that a generator is able to provide to each electron. Unit: Volts (V) The current intensity (I) is the charge that passes through the section of a conductor each second. Or the amount of electrons flowing. Unit: Amps (A) or miliamps (ma) Resistance (R) is the opposition by a material to the passage of electricity. Unit: Ohm (Ω) They are related to one another using Ohm s law: Oxford University Press España, S. A. Technology, programming and robotics II 12

13 Electric Circuitos circuits eléctricos and y electronics electrónicos TYPES OF CIRCUITS Oxford University Press España, S. A. Technology, programming and robotics II 1

14 Electric Circuitos circuits eléctricos and y electronics electrónicos Series Combination Parallel Oxford University Press España, S. A. Technology, programming and robotics II 1

15 Circuitos eléctricos y electrónicos Electric circuits and electronics Ammeter in series Voltmeter in parallel Oxford University Press España, S. A. Technology, programming and robotics II 1

16 Series Circuitos circuits en serie Two or more components of a circuit are in series when the output of one is the input of the next. The current circulating through all the components is identical, while the total voltage is the sum of the voltages at the ends of each component. I = I 1 = I 2 = I 3 = V = V 1 + V 2 + V 3 + The total resistance is: R = R 1 + R 2 + R 3 + Three light bulbs connected in series. Oxford University Press España, S. A. Technology, programming and robotics II 2

17 Series Circuitos circuits en serie I = I 1 = I 2 = I 3 = V = V 1 + V 2 + V 3 + The total resistance is: R = R 1 + R 2 + R 3 + V = 9 V R = R 1 + R 2 + R 3 = = 18 kω Ohm s law: I = V/R = 9/18 = 0,5 ma V 1 = 3 0,5 = 1,5 V V 2 = 10 0,5 = 5 V V 3 = 5 0,5 = 2,5 V V = 1, ,5 = 9 V Oxford University Press España, S. A. Technology, programming and robotics II 2

18 Parallel Circuitos circuits en paralelo Two or more components of a circuit are in parallel when they all have the same input and output. The potential difference of each component is the same however the intensity that circulates along each path varies. I = I 1 + I 2 + I 3 + V = V 1 = V 2 = V 3 = The equivalent resistance of this circuit is: Three light bulbs connected in parallel. Oxford University Press España, S. A. Technology, programming and robotics II 2

19 Parallel Circuitos circuits en paralelo I = I 1 + I 2 + I 3 + V = V 1 = V 2 = V 3 = The equivalent resistance of this circuit is: V = 9 V = V 1 = V 2 = V 3 1 R = = R = = 0,625 kω Ohm s Law: I = V/R = 9/0,625 = 14,4 ma I 1 = V/ R 1 = 9/10 = 0,9 ma I 2 = V/ R 2 = 9/2 = 4,5 ma I 3 = V/ R 3 = 9/1 = 9 ma I 1 + I 2 + I 3 = 0,9 + 4,5 + 9 = 14,4 ma Oxford University Press España, S. A. Technology, programming and robotics II 2

20 Parallel Circuitos circuits en paralelo Oxford University Press España, S. A. Technology, programming and robotics II 2

21 Parallel Circuitos circuits en paralelo EXERCISES Oxford University Press España, S. A. Technology, programming and robotics II 2

22 Electric Circuitos circuits eléctricos and y electronics electrónicos DIRECT CURRENT AND ALTERNATING CURRENT Oxford University Press España, S. A. Technology, programming and robotics II 2

23 Circuitos eléctricos y electrónicos Electric circuits and electronics Direct current is a constant signal produced by a source of energy. Normally, it is used in batterys and generators. Alternating current is the one produced by the electric stations and then transported to our houses to be used. Electrons change their direction 50 times every second. Why do we use alternating current? It is much easier to transport it in long distances because it can be increased or decreased by a transformer. Oxford University Press España, S. A. Technology, programming and robotics II 2

24 Circuitos eléctricos y electrónicos Electric circuits and electronics Oxford University Press España, S. A. Technology, programming and robotics II 2

25 Electric Circuitos circuits eléctricos and y electronics electrónicos EFFECTS OF ELECTRIC CURRENT Oxford University Press España, S. A. Technology, programming and robotics II 2

26 Electric Circuitos circuits eléctricos and y electronics electrónicos Heat Light Sound Movement Oxford University Press España, S. A. Technology, programming and robotics II 2

27 Electric Circuitos circuits eléctricos and y electronics electrónicos Heat The electrons moving often collide, increasing the temperature even of the wire itself. The energy that an electric current produces as heat is called the Joule Effect Oxford University Press España, S. A. Technology, programming and robotics II 2

28 Electric Circuitos circuits eléctricos and y electronics electrónicos Light Incandescent bulbs (normal ones): they use a metal filament Fluerescent tubes: They have a metal filament (tungsteng), gas (argon) and mercury. When current passes through, they react, producing light. They are toxic. LED (light-emitting diodes) Oxford University Press España, S. A. Technology, programming and robotics II 2

29 Electric Circuitos circuits eléctricos and y electronics electrónicos Electromagnetic effects Electric circuits can create magnetic fields. These fields can then be used to produce movement. Michael Faraday discovered the opposite effect. Electricity could be generated by using a magnet and an electrical conductor. Changing the position of the conductor or the magnet, we can generate electric current. Oxford University Press España, S. A. Technology, programming and robotics II 2

30 Electric Circuitos circuits eléctricos and y electronics electrónicos Sound These are electromecanical components, such as buzzers or bells Oxford University Press España, S. A. Technology, programming and robotics II 3

31 Electric Circuitos circuits eléctricos and y electronics electrónicos ELECTROMAGNETIC MECHANISMS Oxford University Press España, S. A. Technology, programming and robotics II 3

32 Electric Circuitos circuits eléctricos and y electronics electrónicos These devices use electromagnetic phenomena to produce electricity. They all use magnets. Dynamos: magnet and a rotary coil. Produce direct current. Alternators: Produce alternating current Electric motors Relays: act like a switch. Oxford University Press España, S. A. Technology, programming and robotics II 3

33 Electric Circuitos circuits eléctricos and y electronics electrónicos To control, we can use limit switch: The difference between the normal switches are that these electromagnetic systems are based on the activation of devices by the actions of moveable parts Normally closed (N/C) Normally open (N/O) Oxford University Press España, S. A. Technology, programming and robotics II 3

34 Electric Circuitos circuits eléctricos and y electronics electrónicos ELECTRONICS Oxford University Press España, S. A. Technology, programming and robotics II 3

35 Electric Circuitos circuits eléctricos and y electronics electrónicos Resistors Transistor Condensers Diode collector emitter Oxford University Press España, S. A. Technology, programming and robotics II 3

36 2. Components Resistors: They make it more difficult for an electric current to pass through a circuit. They are used when you don t need that much electric voltage. They have a color code to identify their value in ohms. Every resistor has three coloured bands, followed by a space and a fourth band. The first two bands: value The third: how many 0s after the first two digits The fourth: tolerance

37 2. Components

38 Practise 2. Components

39 2. Components Practise ohms, 5%: yellow purple red gold ohms, 5%: ohms, 5%: ohms, 10%: ohms, 5%: ohms, 10%: kω, 10%: ohms, 5%:

40 2. Components Variable resistors: Potenciometer: you adjust the value of the resistance Thermoresistors: depends on temperature. Negative temperature coefficient (NTC): The resistance decreases as the temperature rises. Positive temperature coefficient (PTC): The resistance increases as the temperature rises. LDR or photoresistors: depends on the amount of light. More light = less resistance. These are often use as sensors for security systems.

41 Capacitors: 2. Components They store electrical charge. They don t replace a battery, but they are used as an electric filter. Unit: farad (F)

42 2. Components Diodes: Made with semiconductor materials. They have two terminals, anode and cathode. Only allow electric current to flow in one direction. LED (Light-emitting diodes). They work between 10 ma and 20 ma. That is why we need to put a resistor in between the battery and the LED.

43 2. Components Transistors: Made of semiconductor materials (silicon). They are used as switches and signal amplifiers. They have three terminals, base, emitter and collector. There are 2 types: NPN and PNP. They work as switches: they release electrons (N) or accepts electrons (P). They allow a small current to pass through the base in order to produce a much higher current in the collector. They were/are used in all electronic devices. It is probably the biggest advance in electronic history. A phone has billions.

44 2. Components Integrated circuits: They are miniature electronic circuits. They have transistors, diodes and resistors in them.

45 2. Components

46 2. Components