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Resistance. Resistance  As space narrows the resistance to movement increases.

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Presentation on theme: "Resistance. Resistance  As space narrows the resistance to movement increases."— Presentation transcript:

1 Resistance

2 Resistance  As space narrows the resistance to movement increases

3 Electrical Resistance  Where do we find the resistance in a light bulb?

4 What is resistance?  The "resistance to flow of electricity through a material." electricity electricity  Even the best Conductors, (i.e. Gold) have some Resistance.  Resistance Elements fall somewhere between a Conductor and an Insulator.  Resistance can also be considered a measurement of how tightly a material holds onto its Electrons

5  Electrical Resistance is measured in "ohms."  The lower the Resistance of a material, the better the material acts as a Conductor.  Copper has a lower Electrical Resistance than Aluminum; Copper is a better Conductor.  The "resistance value" for most materials is listed in physics or science books.

6 Like….water – what else?  We can use a water piping system as an analogy.  The Resistance in the Water Pipe to the flow of water comes mainly from the size of the Pipe.  Rust and corrosion inside the Pipe, objects stuck inside the Pipe, and the number of "bends" and Fittings all add up to increase the Resistance to the flow of water.

7  The same is true of current flow in an Electric Circuit.  A number of factors determine the Resistance to current flow  Wire diameter  Wire length  impurities in the wire's makeup.  For example, smaller wires have more Resistance than larger diameter wires  Longer wires have more Resistance than shorter wires.

8 Light Bulbs  When electricity flows through any Resistance, energy is dissipated in the form of heat.  If the heat becomes intense enough, the Conductor Resistor may actually "glow".  This is how an Incandescent Light Bulb works.  The Filament is made of a material that will resist the current enough to heat up and "glow".

9  Symbol for Electrical Resistance, ( measured in "Ohms,“) is the Greek letter "Omega". Ω  Electricians and practical Wiring Books typically use an "R" to represent Resistance.


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