If atoms start out as neutral, how do we know which material becomes positively charged and which material becomes negatively charged? Truemper 2016

An object can be… Truemper 2016

Truemper 2016

Static Electricity

What Is Static Electricity? A stationary electrical charge that is built up on the surface of a material

Where do charges come from? Matter is made up of atoms. + – atom nucleus

Where do charges come from? If electrons = protons neutral If electrons > protons  negative charge (gains electrons) If electrons < protons  positive charge (loses electrons)

Where do charges come from? When a balloon rubs a piece of wool... electrons are pulled from the wool to the balloon. + – – The balloon has more electrons than usual. wool The balloon: – charged, The wool: +charged

Insulators Insulators: materials that do NOT allow electrons to flow through them easily. Insulators can be easily charged by friction as the extra electrons gained CANNOT easily escape.

Conductors Conductors: materials that allow electrons to flow through them easily. Conductors CANNOT be easily charged by friction as the extra electrons gained can easily escape.

Where do charges come from? Rubbing materials does NOT create electric charges. It just transfers electrons from one material to the other.

Conductors and Insulators Copper Rubber Aluminum Cloth Humans Hair Water Plastic Most metals Glass Paper

If atoms start out as neutral, how do we know which material becomes positively charged and which material becomes negatively charged? Truemper 2016

Truemper 2016

So which object becomes negatively charged? Truemper 2016

So which object becomes negatively charged? Truemper 2016

Truemper 2016

Aluminum becomes negatively charged Styrofoam becomes negatively charged Teflon becomes negatively charged Polyethylene becomes negatively charged Truemper 2016

Grounding Using a conductor to move an electric charge to the ground. An object is grounded when it is connected to the earth. Using a conductor to move an electric charge to the ground.

How does grounding occur? When we touch a metal sphere of positive charge... + + electrons flow from the earth to the metal to neutralize the metal. + + + – Metal becomes neutral.

Grounding How does grounding occur? Similarly, if the metal is of negative charge... – – extra electrons flow from the metal to the earth and the metal becomes neutral. – – – –

Truemper SciLesson

Discharge Static Electric

Electric Discharge The release of built up electrons from one charged material to a neutral or oppositely charged material.

What will happen as the man walks across the room? Truemper SciLesson