Here We Have a Battery Light Bulb and some Wires because these Wires Are Not Connected this Is Called an Open Circuit no Electricity Can Flow

When We Touch the Probes Together the Circuit Is Completed and the Light Bulb Glows Cardboard Does Not Conduct as We See When We Touch both Probes to It the Quarter Which Is Made out of Metal Does Conduct but the Plastic Lens Cap Does Not Now We'Ll Use this Device To Test the Conductivity of some Liquids Here We Have Distilled Water or Pure Water on the Left and Tap Water on the Right We'Ll Add another Label to the Bottom of the Containers Well Turn Out the Light so We Can See the Flashlight Better Notice It Does Not Light Up At All in the Distilled Water Distilled Water Is a Nonconductor However When We Dip the Probes into Tap Water the Light Glows a Little Bit Tap

We'Ve Created a Table That We Can Use To Record Our Results in the Left Column We'Ll Name the Liquid or Solution and in the Right Column Will Note the Conductivity of each Liquid or Solution Remember the Liquid on the Left Was Distilled Water and the Distilled Water Has no Conductivity It's a Nonconductor Tap Water Was in the Beaker on the Right Remember the Flashlight Lit Up a Little Bit so It's Conductivity Was Slate Now We'Ll Compare the Connectivities of Tap Water on the Leftist Time and Salt Water or Salt

Now We'Ll Compare the Connectivities of Tap Water on the Leftist Time and Salt Water or Salt Solution Which We Have Placed in the Container on the Right

First We'Ll Talk about Salt Solution and Explain Why It's Conductivity Is So High We Can Think of a Solid Salt Crystal as Being Made Up of a Large Number of Tiny Particles Called Ions Half of these Ions Have a Positive Charge and Half of Them Have a Negative Charge the Attraction between Positive and Negative Charges Keeps these Ions Together in the Crystal Remember this Is Only a Simple Model the Actual Ions Would Be Much Too Small To See and It Would Be Billions of Them in a Single Crystal

This Is Only a Simple Model the Actual Ions Would Be Much Too Small To See and It Would Be Billions of Them in a Single Crystal When We Add Water to the Container the Water Causes the Ions and the Salt To Break Apart and Spread Out throughout the Water

This Model Represents a Solution of Salt Now We'Ll Add Two Probes from the Conductivity Tester One of the Probes Will Have a Positive Charge and the Other One Will Have a Negative Charge because Opposite Charges Attract the Positive Ions Move toward the Probe on the Right

When We Dip Our Probes into the Sugar Solution the Neutral Molecules Are Not Attracted to these Probes There Are no Charged Ions That Move in this Solution Therefore There Is no Flow of Charges

When Water Is Added to Pure Acetic Acid the Molecules Spread Out Evenly To Form a Solution Most of these Molecules Remain Neutral but a Few of Them Break Up and Form Ions so Vinegar Solution Is Mainly Neutral Molecules with Only a Small Number of Positive and Negative Ions Present When Positive Negative Probes from Our Conductivity Tester Are Dipped into a Vinegar Solution the Negative Ions Move toward the Positive Probe and the Positive Ions Move towards a Negative Probe

Now We'Ll Dip Positive and Negative Probes from Our Conductivity Tester into the Pure Water Water Molecules

Intro

Drude model of electrical conductivity

Sommerfeld model

Experimental resistivity of metals