ResistanceResistance

ResistanceResistance

As space narrows the resistance to As space narrows the resistance to movement increasesmovement increases

Electrical ResistanceElectrical Resistance

Where do we find Where do we find the resistance in a the resistance in a

light bulb?light bulb?

What is resistance?What is resistance?

The "resistance to flow of The "resistance to flow of electricityelectricity through a through a material." material."

Even the best Conductors, (i.e. Gold) have some Even the best Conductors, (i.e. Gold) have some ResistanceResistance. .

Resistance ElementsResistance Elements fall somewhere between a fall somewhere between a Conductor and an Insulator. Conductor and an Insulator.

ResistanceResistance can also be considered a measurement of can also be considered a measurement of how tightly a material holds onto its how tightly a material holds onto its ElectronsElectrons

Electrical ResistanceElectrical Resistance is measured in "ohms." is measured in "ohms." The The lowerlower the the ResistanceResistance of a material, the of a material, the

betterbetter the material acts as a Conductor. the material acts as a Conductor. Copper has a Copper has a lowerlower Electrical ResistanceElectrical Resistance than than

Aluminum; Copper is a Aluminum; Copper is a betterbetter Conductor. Conductor. The "resistance value" for most materials is The "resistance value" for most materials is

listed in physics or science books. listed in physics or science books.

Like….water – what else?Like….water – what else?

We can use a We can use a water piping systemwater piping system as an analogy. as an analogy. The The ResistanceResistance in the Water Pipe to the flow of water in the Water Pipe to the flow of water

comes mainly from the size of the Pipe. comes mainly from the size of the Pipe. Rust and corrosion inside the Pipe, objects stuck Rust and corrosion inside the Pipe, objects stuck

inside the Pipe, and the number of "bends" and inside the Pipe, and the number of "bends" and Fittings all add up to increase the Fittings all add up to increase the ResistanceResistance to the to the flow of water. flow of water.

The same is true of The same is true of current flowcurrent flow in an Electric in an Electric Circuit. Circuit.

A number of factors determine the A number of factors determine the ResistanceResistance to to current flowcurrent flow Wire diameterWire diameter Wire length Wire length impurities in the wire's makeup. impurities in the wire's makeup.

For example, smaller wires have more For example, smaller wires have more ResistanceResistance than larger diameter wires than larger diameter wires

Longer wires have more Longer wires have more ResistanceResistance than than shorter wires. shorter wires.

Light BulbsLight Bulbs

When When electricityelectricity flows flows through any through any ResistanceResistance, , energyenergy is dissipated in the is dissipated in the form of form of heatheat. .

If the If the heatheat becomes intense becomes intense enough, the Conductor enough, the Conductor Resistor may actually "glow".Resistor may actually "glow".

This is how an Incandescent This is how an Incandescent Light Bulb works. Light Bulb works.

The Filament is made of a The Filament is made of a material that will resist the material that will resist the currentcurrent enough to heat up and enough to heat up and "glow". "glow".

Symbol for Symbol for Electrical ResistanceElectrical Resistance, ,

( measured in "Ohms,“) is the Greek letter ( measured in "Ohms,“) is the Greek letter "Omega". Ω"Omega". Ω

Electricians and practical Wiring Books Electricians and practical Wiring Books typically use an "typically use an "RR" to represent " to represent ResistanceResistance. .