• Electric Circuit– Current provided by battery flows through wire, into the

light bulb, through another wire, and back to the battery.• Current: flow of electrons

Insulators and Conductors

Conductor lets electrons flow

Insulator doesn’t let electrons flow

Electric lamp

(glowing)

Electric lamp

(not glowing)

Bat

tery

•Pencils are a good demo, touch the wires to the wood (no light), then touch them to the graphite (the LED lights up).•Try sliding the loose ends of the wires closer & farther, it may effect the LED’s brightness -more distance the higher the resistance in the circuit.•The Multi-meter isn’t so much for the testing of conductivity in this instance, it can be but the numbers usually loose the kids. It mostly serves to show the older kids that conductivity/resistance can be directly quantified.

Applications of Insulators and ConductorsSuperconductors

Zero Resistance Infinite conductivityOnly at very low Temperature

High-Voltage Transmission Lines:Up to 765,000 Volts Wires are Copper

Insulators are ceramic (they used to be glass).

High-Tension wires

Computers have printed circuit boards with copper lines connecting different

Silicon chips.High-Voltage Breakdown Insulators

Silicon is a semiconductor it can conduct or insulate

Insulators and Conductors

Insulators hold electrons close like a

dog on a leash

Conductors let electrons flow like dogs running free

Atoms

Insulators let electrons flow like dogs running free

Conductors let electrons go. They travel anywhere in

the material.

Free electrons from outer shells of metal atoms can move throughout material

Metal ions (+) remain stationary

There are NO free electrons, electrons are shared between atoms in bonds.

Metal ions (O) remain stationary

• Resistance: How much the material resists the flow of electrons

R = V / I• The higher the resistance, the slower the flow of

electrons, the smaller the power output

Resistance

R = ( x L) / A

R - Resistance - Density L - Length

A - Area

Higher Resistance

Lower Resistance

Resistance: is like resistance to water flow in a hose. Larger diameter hose -less resistance, longer hose –more resistance

Voltage like pressure, current like flow