Section 2- Electricity Mind Map

Section 2- Electricity Mind Map covers snap shots of all information in the Topic

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  • Electricity
    • Safe Plugs
      • Plugs must not have incorrect wiring
        • No bare wire showing inside
        • The cable cover is tightly fasten over the insulation of the cable
      • Anything which plugs into the wall must be earthed or insulated
        • The live wire changes between positive and negative, therefore being Alternating current at 230 V or 110V (depends what country)
        • The Neutral Wire is always at 0 V
        • Earth Wire and Fuse is a safety feature which protects you from electrocaution
        • Plastic round copper wires is an insulator, so you don't get a shock. If it has double insulation, it is enough to protect you from getting shocked
      • Some Safety Measures should be taken
        • Check plug is not damaged, Check cable for fraying. Check No water anywhere near appliance
        • Never push metal object into plug
        • Check cables are not stretching over walkways, which is a trip hazard
    • Fuses and Circuit Breakers
      • Fuses and Earthing lines prevent fire and shock
        • If a fault develops with the live somehow touches the metal case, the current flows though the earth wire which connects the case preventing user from getting shocked
      • Circuit Breakers have some advantages over fuses
        • A circuit breaker works when it detects too high a current like a fuse but instead of the current melting a wire. The circuit breaker opens a switich
        • One type is a Residual Current Circuit Breaker
          • They are much better than fuses in they cut current off immediately. This is better than waiting for fuse wire to melt.
          • They even work for small circuits as well
    • Energy and power to circuits
      • Resistors get hot when an Electric Current passes though it
      • Electrical Power and Fuse Rating
        • Electrical power is the rate at which an appliance transfers energy
        • An Electrical appliance with a high power rating like a kettle, means lots of energy in a short period
        • Formula: Electrical Power= Current X Voltage
        • The most common fuses are 3A, 5A and 13 A
      • Electrical Devices transfer electrical energy
        • When current flows though a component energy is transferred.
          • For example, current travels though a light bulb, electrical energy is transfer to light and heat energy
        • Formula: Energy Transferred= current X Voltage X Time
    • Circuits- The basic
      • 1- Current is the rate of flow of charge round the circuit
      • 2-Voltage is the driving force that pushing current round
      • 3- Resistance is anything in the circuit which slows the flow down
      • If you increase the voltage- then more current will flow.
        • If you increase the resistance- Then less current will flow
      • A Simple Circuit
        • An Ammeter measures the current in amps flowing round the circuit. Must be connected in Series
        • A Voltmeter measures the voltage in volts but must be connected in parallel
    • Resistance (R=VI)
      • Formula: Resistance= Voltage/ Current
      • Four Important Voltage- Current Graphs
        • Metal Filament Bulb: As the temp of the metal filament increase, the resistance increases
        • Different Resistors: They have different resistances. The current though a resistor at constant temp is proportional to the voltage.
        • Diode: Current will only flow though a diode in one direction
        • Wire: The current though a wire at constant temp is proportional to voltage
    • Light depend resistor, Thermistors and Light emitting diodes
      • Light- Emitting Diode
        • They emit light when current flows though them in a forward direction
        • They are used to indicate the presence of current in a circuit. They are often used in appliances to show that they are switched on.
      • Some components can change resistance
        • Light Dependent Resistor
          • LDR is a special type of resistor that changes its resistance depending on how much light falls on it
          • In bright light, the resistance is highest
          • It can be used for electronic circuits like burglar detectors
        • Thermistor
          • A Thermistor is a temperature- dependent resisitor
          • Thermistors make useful temperature detection. For example, car engine temp sensors
          • In warm conditions, the resistance drops and in cool conditions, the resistance goes up
    • Series and Parallel Circuits
      • Series Circuit
        • In a series circuit, the different components are connected in a line
        • Current is the same every where in the circuit, so Ammeter 1 and 2 will read the same
      • Parallel
        • If you remove one light bulb out of five light bulbs, it will hardy effect the circuit
        • Ammeters are the expections to parallel and have to be connected in a series circuit
    • Charge, voltage and energy change
      • Charge though a circuit depends on current and time
      • Formula: Charge (Coulombs)=Current (amps) X Time (seconds)
      • When a charge drops though a voltage it transfers energy
      • One Volt is one joule per coulomb
      • Voltage is the energy transferred per unit charge passed
      • More charge passes around a circuit when a bigger current flows
    • Static Electricity
      • Conductors conduct charge
        • Material which are conductors charge allowing a current to pass though. For example, Copper or Gold
        • Materials which are insulators don't conduct letting current pass over them. Examples are plastic and rubber
      • Build up of static is caused by friction
        • When two insulating materials are rubbed together electrons will be scraped off one and dumped on the other
        • Only Electrons Move- Never the positive charge
        • Both positive and negative electrostatic charges are only ever produced by the  movement of electrons.
        • A charged conductor will discharge safety by connecting it to the earth wire with a metal strip
      • Examples of Static Electricity and How it is dealt with?
        • Van de Graaff Generator which shows you electrostatic change.  When person's hands touch it while standing on an insulator. It makes your hair stand on end.
        • Static Electricity Being Helpful
          • Inkjet Printers
            • Tiny Droplets of ink forced out of a fine nozzle making them charged
              • The Droplets are deflected as they pass between two metal plates and finally landing on the paper
          • Photocopier
            • The Image plate is positively charged while an image is projected on to it. The white bits leak away but the negative charged are coated in black powder and then heated on to the paper
        • Static Electricity Being a Problem
          • Lightning
            • Rain Drops and Ice bump together inside storm clouds, knocking off electrons and it has a positive charge at the top and negative and bottom of cloud which creates a huge spark
          • Refueling Aircraft
      • Like charges Repel, Opposite charges attract
  • For example, current travels though a light bulb, electrical energy is transfer to light and heat energy
  • The greater the charge on an isolated objet, the greater the voltage between it and earth
    • As charge builds up, So Does the voltage- Causing Sparks
      • Build up of static is caused by friction
        • When two insulating materials are rubbed together electrons will be scraped off one and dumped on the other
        • Only Electrons Move- Never the positive charge
        • Both positive and negative electrostatic charges are only ever produced by the  movement of electrons.
        • A charged conductor will discharge safety by connecting it to the earth wire with a metal strip

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