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What are some of the ways in which electricity can be provided in remote locations?

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What are some of the ways in which electricity can be provided in remote locations?

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  1. 1. Society has become increasingly dependent on electricity over the last 200 yearsWhat do you know about the debate that took place between Volta and Galvani about animal and chemical electricity? How did it contribute to increased understanding about electricity?How have the main sources of domestic energy have changed over time?What are some of the impacts of changes in, and increased access to, sources of energy for a community? What are some of the ways in which electricity can be provided in remote locations?

  2. + + + - - - + - 2. One of the main advantages of electricity is that it can be moved with comparative ease from one place to another through electric circuitsBehaviour of electrostatic charges and the field associated with them ATTRACTION REPULSION IN or OUT? Remember: the unit of electric charge is the COULOMB (C) ELECTRIC FIELDS? Do you know what a millicoulomb and microcoulomb are? prefixes? sci.notation?

  3. F = qE 700 V F = mg Describe the electric field as a field of force with a field strength equal to the force per unit charge at that point: E =F/q + 200 V - 1. Which is the positive plate? 2. What direction would the electric field be? 3. Is this particle positively or negatively charged? 4. What two forces act on a charged particle between the plates? Equations? Direction? 5. How can we change the strength of the field?

  4. Current is the rate at which charge flows (C/s or amperes) under the influence of an electric fieldCurrent can be eitherdirect with the net flow of charge carriers moving in one direction (D.C.)or alternating with the charge carriers moving backwards and forwards periodically(A.C.)

  5. 10 A 12 W R1 240 V R2 4 W R3 8 W Potential difference (voltage) between two points is the change in potential energy per unit charge moving from one point to the other (joules/coulomb or volts)Discuss how potential difference between different points around a circuit varies 240 V 120 V 0 V 80 V

  6. Conductors have electrons in their atoms which flow easily • Insulators have outer electrons in their atoms which do not flow easily For conductors: longer means more resistance larger cross-sectional area means less resistance resistance may also vary with temperature (high temp more resistance in metals) and type of material (different electron bond strengths)

  7. 10 A 12 W 240 V R ? 8 W RT = VT / IT = 240/10 = 24 W R = 24 - 12 - 8 = 4 W Solve problems and analyse information applying V = IR e.g. ... V = IR VT = IT .RT

  8. 10 A 12 W R1 240 V R2 4 W R3 8 W 3. Series and parallel circuits serve different purposes in households Resistors in SERIES • Resistors on one branch of circuit • Total resistance RT = R1 + R2 + R3 ...... • Current is the same for each of resistors in series • Voltage drops vary - use Ohm’s Law SWITCHES ARE IN SERIES WITH DEVICES IN YOUR HOME -- WHY?? ( so are some painful Christmas lights! )

  9. 10 A 240 V R1 R2 R3 Resistors in PARALLEL • Resistors on different branches of circuit • Total resistance: 1/RT = 1/R1 + 1/R2 + 1/R3 ...... • Voltage is the same for each of resistors in parallel • Current may vary - use Ohm’s Law LIGHTS IN YOUR HOME ARE IN PARALLEL WITH EACH OTHER AS ARE YOUR POWER POINTS - - WHY??

  10. Ammeters and Voltmeters A Ammeter always connected in series to read current THROUGH the resistor V Voltmeter always connected in parallel to read voltage ACROSS the resistor

  11. Explain why there are different circuits for lighting, heating and other appliances in a HOUSE • IF ONE CIRCUIT BLOWS, THE OTHERS DON’T • THE MAIN DIFFERENCE IS HEAVIER GAUGE WIRING IN POWER POINT AND HEATING CIRCUITS (MORE CURRENT) • IT FOLLOWS THAT POWER POINT AND HEATING CIRCUITS HAVE LARGER CAPACITY FUSES AND CIRCUIT BREAKERS

  12. 4. The amount of power is related to the rate at which energy is transformed POWER is related to the rate at which energy is transformed from one form to another P = (change in E)/t P = E/t CAUTION Make sure you use S.I. units e.g. secs not hrs ( P = VI ) VI = E/t VIt = E

  13. What are the advantages and disadvantages of labelling goods with power rating?Why has a simple scale has been used for energy rating on commercial goods and how do these scales relate to potential difference and current? Propose reasons as to why the kilowatt-hour is used to measure domestic electricity consumption rather than the joule You gathered first-hand information to estimate the cost of electricity consumed by your householdDiscuss ways in which consumption could be reduced

  14. 5. Electric currents also produce magnetic fields and these fields are used in different technologies in the home Describe the behaviour of the magnetic poles when they are brought close together The direction of the magnetic field at a point is the direction of force on a very small magnetic pole when placed at that point Describe the magnetic field around single magnetic poles and pairs of magnetic poles Remember the iron filings and the compasses?? What was involved in these experiments? Compare the nature and generation of magnetic fields by solenoids and a bar magnet

  15. Describe the production of a magnetic field by an electric current in a straight current-carrying conductor and describe how the right hand grip rule can determine the direction of current and field lines Make a fist and point your thumb in the direction of the current B I B I B B

  16. Assess the impact of applications of magnetic fields on society Explain one application of magnetic fields in households, such as:telephone or stereo speakersmagnetic tapeand use the available evidence to assess the impact of its use

  17. 6. Safety devices are important in household circuitsDiscuss the effects of an electric shock from both a 240 volt AC mains supply and various DC voltages, from appliances, on the muscles of the body What do voltage and current do to your muscles? p.133-134 Jacaranda text SEE Identify the functions of circuit breakers, fuses and other safety devices in the home Fuses and circuit breakers prevent household circuits from overloading How are insulators and earth wires used in appliances? SAFETY SWITCHES PREVENT ELECTROCUTION

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