1 What is Electricity? How do we produce Electricity? What are the different types of current and how are they produced?

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What is Electricity?What is Electricity?

How do we produce Electricity?How do we produce Electricity?

What are the different types of What are the different types of current and how are they produced?current and how are they produced?

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What is ElectricityWhat is Electricity

• Electricity involves the interaction Electricity involves the interaction of positive and negative chargesof positive and negative charges

• Electricity is essentially the Electricity is essentially the movement of chargemovement of charge

• Electric current is the flow of Electric current is the flow of charge through a conductorcharge through a conductor

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Key Electricity terms:Key Electricity terms:

1.1. Voltage: Force pushing electronsVoltage: Force pushing electrons

2.2. Current: number of electrons flowing; Current: number of electrons flowing; frequency of e- flowfrequency of e- flow

3.3. Resistance: how easy or difficult it is Resistance: how easy or difficult it is for e- to flowfor e- to flow

4.4. Conductors: have low resistance Conductors: have low resistance

5.5. Insulators: have high resistanceInsulators: have high resistance

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How do we produce How do we produce electricity?electricity?

1.1. Static; frictionStatic; friction

2.2. Generators: Generators: hydroelectric, hydroelectric, nuclear, coal, nuclear, coal, natural gas, natural gas, biomass, tidal, hand biomass, tidal, hand crank radiocrank radio

3.3. MagnetismMagnetism

4.4. Solar cellsSolar cells

5. Chemical reactions; batteries

6. Piezoelectricity; using crystalline flux

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Different types of Electric Different types of Electric current:current:

• DC= Direct DC= Direct CurrentCurrent

• This is current This is current that flows in one that flows in one direction from direction from positive to positive to negative charged negative charged areasareas

• AC=Alternating AC=Alternating CurrentCurrent

• This is current This is current that flows back that flows back and forth, and forth, alternating alternating direction of flowdirection of flow

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What makes DC?What makes DC?

• Static dischargesStatic discharges• BatteriesBatteries• DC converters/DC converters/

adaptersadapters

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Static ElectricityStatic Electricity

• Made by the Made by the transfer of charge transfer of charge due to frictiondue to friction

• Very dry air Very dry air promotes static promotes static electricity, moist electricity, moist or humid air or humid air reduces itreduces it

•Lightening is the greatest form of static electric

discharge.

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DC and BatteriesDC and Batteries

• Batteries use a Batteries use a chemical reaction chemical reaction to produce a flow to produce a flow of charge. of charge.

• Batteries can be Batteries can be Wet Cell or Dry Wet Cell or Dry Cell in natureCell in nature

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More about BatteriesMore about Batteries

• Wet Cells:Wet Cells:• Used in cars, lawn Used in cars, lawn

mowers, boatsmowers, boats• Often have lead Often have lead

compound anodes compound anodes and cathodes and and cathodes and use a liquid use a liquid electrolyteelectrolyte

• Maximum voltage Maximum voltage per cell is 2 Voltsper cell is 2 Volts

• A simple one can be A simple one can be made with a copper made with a copper strip, a zinc strip and strip, a zinc strip and an electrolyte such an electrolyte such as Hydrochloric acid as Hydrochloric acid or even Lemon Juiceor even Lemon Juice

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More about BatteriesMore about Batteries

• Dry CellsDry Cells• Used in small Used in small

appliances, appliances, radios, remote radios, remote controlscontrols

• Often made of a Often made of a zinc case and zinc case and carbon center rod carbon center rod and a dry or paste and a dry or paste electrolyteelectrolyte

• Maximum voltage Maximum voltage per cell is 1.5 per cell is 1.5 VoltsVolts

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Dry Cell types:Dry Cell types:

• The size AAA, AA, The size AAA, AA, C, and D C, and D “batteries” that “batteries” that we use are single we use are single dry cells; they are dry cells; they are not true batteriesnot true batteries

• A battery is 2 or A battery is 2 or more cells wired more cells wired togethertogether

• The maximum The maximum voltage available voltage available from any single from any single dry cell is 1.5 dry cell is 1.5 volts, so why so volts, so why so many different many different types. AAA=1.5Vtypes. AAA=1.5V

D=1.5VD=1.5V

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More about batteries and More about batteries and single cells:single cells:

• So how is a 9V built?So how is a 9V built?• How does a car How does a car

battery have 12V?battery have 12V?• How does a camping How does a camping

lantern battery have lantern battery have 6V while the same 6V while the same size hobby battery size hobby battery has 1.5V?has 1.5V?

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More about batteries and More about batteries and single cells…single cells…

• A 9V battery has 6 A 9V battery has 6 smaller dry cells in it smaller dry cells in it

• A car battery has 6 A car battery has 6 smaller wet cells smaller wet cells

• A lantern battery has A lantern battery has 4 dry cells wired in 4 dry cells wired in series and a hobby series and a hobby battery has 4 dry battery has 4 dry cells wired in parallelcells wired in parallel

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Good and Bad of Wet and Good and Bad of Wet and Dry cells:Dry cells:

Wet CellsWet Cells• Bad: often use acid Bad: often use acid

electrolyteselectrolytes• Bad: tend to be large Bad: tend to be large • Good: can be Good: can be

rechargedrecharged• Good: produce more Good: produce more

Voltage per cellVoltage per cell

Dry CellsDry Cells• Bad: cannot be Bad: cannot be

rechargedrecharged• Bad: only produce Bad: only produce

1.5 Volts per cell1.5 Volts per cell• Good: some can be Good: some can be

rechargedrecharged• Good: smaller and Good: smaller and

lighter and usually do lighter and usually do not corrode not corrode applianceappliance

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DC AdaptersDC Adapters

• Used to convert AC Used to convert AC to DC for appliance to DC for appliance useuse

• Range in sizes from Range in sizes from very small Voltages very small Voltages to very large to very large voltagesvoltages

• A telephone may use A telephone may use 9 V while a laptop 9 V while a laptop computer often uses computer often uses 18 V18 V

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What makes AC?What makes AC?

• Generators: Generators: change change mechanical mechanical energy into energy into electrical energy electrical energy with the use of with the use of magnetsmagnets

• It is available It is available through any wall through any wall outletoutlet

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How does a generator How does a generator work?work?

• A generator turns A generator turns a magnet in a magnet in between coils of between coils of wire and the wire and the magnetic field magnetic field induces an induces an electric charge electric charge flow in the coils of flow in the coils of wirewire

• Different Different directions of directions of current flow are current flow are created as the created as the magnet turns magnet turns causing the causing the direction changing direction changing characteristic of characteristic of ACAC

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More about ACMore about AC

• AC is produced at AC is produced at certain frequencies certain frequencies of cycles due to the of cycles due to the spinning of the spinning of the magnets in the magnets in the generators usedgenerators used

• The frequency of The frequency of these cycles varies these cycles varies around the worldaround the world

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AC Stats.AC Stats.

• The U.S. produces The U.S. produces AC at 60Hz (cycles AC at 60Hz (cycles per second) and per second) and household outlets household outlets are 120 Volts and are 120 Volts and large appliance large appliance outlets are 220 Voutlets are 220 V

• The UK is at The UK is at 50Hz and 230V50Hz and 230V

• Japan is at Japan is at 50/60Hz and 50/60Hz and 100V100V

• Australia is at Australia is at 50Hz and 230V50Hz and 230V

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Problems with travel and different Problems with travel and different AC frequenciesAC frequencies

• If you purchase an If you purchase an appliance that is only appliance that is only set to US it will not work set to US it will not work in most other countriesin most other countries

• The plugs are not the The plugs are not the same eithersame either

• You would need to You would need to purchase a set of purchase a set of adapter plugs and adapter plugs and purchase appliances purchase appliances that are adaptablethat are adaptable

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Possible Pros and Cons of Possible Pros and Cons of AC and DCAC and DC

• Pros: AC is Pros: AC is easier/cheaper to easier/cheaper to produce and produce and control in large control in large quantitiesquantities

• Pros: DC is Pros: DC is needed for many needed for many electronic electronic components and components and it is easy to it is easy to transporttransport

• Cons: AC Cons: AC production production requires a requires a generator and generator and other suppliesother supplies

• Cons: DC Cons: DC batteries are batteries are expensive and expensive and have a limited have a limited lifespanlifespan