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Electricity
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- 2. What do youuse electricity for?
- 3. ELECTRICITY Electricity is aconvenient and clean form of energy that is very commonly used in our everyday lives. Electricity heater mobile phone lamp TV fan microwave electric toothbrush remote control garage door air aconditioning banner glass ceramic hob
- 4. ELECTRICITY Electricity is aform of energy, like thermal/heat, light, mechanical or acoustic/sound energy. But Electric Energy: • Iluminates bulbs (light energy) • Heats up the food (thermal energy) • Moves engines (mechanical energy) • Is transformed into sound waves in the loudspeakers (acoustic energy) Electricity
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- 6. Atomicparticles All matter iscomposed of atoms, and atoms are made up of other smaller particles: • Electrons: which have negative charge and are responsible for electric forces and interactions. • Protons: which have positive charge. • Neutrons: which don´t have charge. In general, matter is neutral.
- 7. Two objects withthe same charge repel each other. Two objects with different charge attract each other. In the world of static electricity… Oppositely charged objects attract Objects with like charges repel Electriccharges
- 8. We talk aboutstatic electricity when there is a movement of electrons from one material to another (only electrons can move from one atom to another). Staticelectricity And since UNLIKE CHARGES ATTRACT, the two materials will attract each other. When two different materials are rubbed together, often electrons are transferred from one to the other. Then the two materials will become oppositely charged.
- 9. Static electricity isan imbalance of electric charges on the surface of an insulator material that remains until it is able to move away by means of an electrical discharge. Some manifestations of static electricity are: Lightning Photocopier: The toner is attracted to dark patches that keep static charges. Painting Staticelectricity
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- 11. Electrical current isthe continual movement of electrical charges (electrons) through an appropriate path. This path must be done with a good conductor material, not with an insulator Electrical current Metals are good conductor materials. Wires are made of copper and are covered with a plastic cover (plastic is a electrical insulator and protects us).
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- 13. Electrical circuit isa set of elements connected to one another so that electrical current can circulate through them. For an electric current to flow through an electrical circuit we need to things: Something to make electricity flows. A complete path Electrical current
- 14. In this circuit,electricity flows from the negative side of the battery, through the wires, and lights the bulb. Then, the electricity continue traveling around to the positive side of the battery. Electrical current This process is continually repeated. In this circuit we have: Something to make electricity flows, the battery. A complete path
- 15. The simplest circuitis a piece of wire from one end of the battery to the other. Electricalcircuit An electric current flows in the wire from one end of the battery to the other, but nothing useful happens. The wire just gets hot and the battery wears out. So, ANOTHER ELEMENT IS NECESSARY in this circuit.
- 16. Electricalcircuit We need toadd an electrical component into the circuit that can use the current to make something happen. ANOTHER ELEMENT IS NECESSARY in the previous circuit, in order to do something useful with the electric current In this situation , the bulb transforms the electrical energy into light energy, so we can see in the night. We also can use an engine, that transforms the electrical energy into mechanical energy, so we can make a fan works.
- 17. Electricalcircuit We need toadd an electrical component that allow us to turn the circuit on or off when we want, that is, to control the circuit. But in this circuit, ANOTHER ELEMENT IS NECESSARY, in order to avoid the bulb is always working. o Switches o Commutator switches o Push buttons We can control the circuit with:
- 18. Electricalcircuit A high currentwill break the fine wire in the fuse, so the circuit is broken an electricity doesn´t flow, so, nothing can be damaged. And ANOTHER ELEMENT IS NECESSARY (but less necessary), in order to avoid the components of the circuit to be damaged.
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- 20. Circuit diagrams They are usedcircuit symbols to draw diagrams of electrical circuits instead of drawing each component in it. Wires always must be straight lines and not wiggly.
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- 22. Serialand parallelcircuits In a seriescircuit, you get several components one after the other; there are no branches. The electrons pass through all the different components, one after the other.
- 23. Serialand parallelcircuits In a seriescircuit, you get several components one after the other; there are no branches. If you put more lamps into a series circuit, the lamps will be dimmer than before. If a lamp breaks or a component is disconnected, the circuit is broken (opened) and all the components stop working.
- 24. Serialand parallelcircuits In a parallelcircuit, you get different components connected on different branches. The electrons don´t pass through all the components, only through the components in a branch.
- 25. Serialand parallelcircuits In a parallelcircuit, you get different components connected on different branches. If you add more lamps in parallel, the lamps stay bright. If a lamp breaks or a component is disconnected from the parallel wire, the components of different branches keep working.
- 26. Serialand parallelcircuits In a combinedcircuit there are serial and parallel components in the same circuit.
- 27. Electrical quantities VOLTAGE is thedifference between the electrical energy at two points in a circuit. When there is a difference of the electrical energy, charges move from the point where the energy is highest to the lowest point. Voltage is also called potencial difference (p.d.)
- 28. Electrical quantities VOLTAGE is thedifference between the electrical energy at two points in a circuit. Voltage is measured with a voltmeter. If we want to measure the voltage of a component in a circuit, the voltmeter must be connected in parallel. Voltage is represented by the letter V and in the International System of Units (SI) is measured in volts (V).
- 29. Electrical quantities The CURRENT isthe number of electrons that pass through a specific point in one second. Current is represented by the letter I and in the International System of Units (SI) is measured in amperes or amps (A). Current is measured with an ammeter. If we want to measure the current through a receptor, the ammeter must be connected in series.
- 30. Electrical quantities The RESISTANCE isthe opposition of the components of a circuit to the flow of electric current. Resistance is represented by the letter R and in SI units is measured in ohms (W).
- 31. Ohm´slaw The a relationshipbetween voltage, current and resistance is called Ohm´s law. Ohm´s law is expressed mathematically as: 𝑉 = 𝐼 ∙ 𝑅 𝐼 = 𝑉 𝑅 𝑅 = 𝑉 𝐼 And it can also be expressed as:
- 32. Effectsofthe electricalcurrent Light Magnetism / Motion Heat:basically all components heat up when are crossed by an electrical current Electrical current can cause different effects as it flows through the components of the circuit
- 33. Equivalent resistances All elements ofan electrical circuit heat up when are crossed by an electrical current, that is all elements have resistance. So, a bulb or a motor can be replaced with a resistor
- 34. Equivalent resistances It is importantto calculate the equivalent resistance in a serial, parallel or combined circuit in order to calculate the voltage, intensity of current or resistance of each element in the circuit. Equivalent resistance
- 35. Equivalent resistances Equivalent resistance forresistors in series circuits R1 R2 RT 𝑅 = 𝑅1 + 𝑅2 + 𝑅3 + ⋯ Equivalent circuit Equivalent resistance
- 36. Equivalent resistances Equivalent resistance forresistors in series circuits 1 𝑅 = 1 𝑅1 + 1 𝑅2 + 1 𝑅3 + ⋯ RT R1 R2 If we only have two resistors, we can use the following formula: 𝑅 = 𝑅1 ∙ 𝑅2 𝑅1 + 𝑅2 Equivalent circuit Equivalent resistance