Electricity Quiz

Electricity

A form of energy that results from charged particles.

The smallest particles that exist

atoms

What are in atoms?

A nucleus, protons, electrons and neutrons

An electrical charge

produced when an atom gains or loses electrons.

What is ordinarily uncharged

An atom is ordinarily uncharged, but can gain or lose electrons through friction or rubbing together (static electricity).

A positive charge

Created when there are more protons than electrons.

A negative charge

Created when there are more electrons than protons.

Electrical energy

The movement of electrons through a conductor.

How can electrical charges be moved?

In a stream or path through conductive materials.

Static electricity

The buildup of an electrical charge on the surface of an object. Static electricity stays in one place.

Example of static electricity

When you rub your socks against the carpet and then you feel a shock

When does a static charge happen?

A static charge happens when two surfaces rub together and the electrons move from one object to another.

Charging by Contact

When two different materials touch, electrons transfer.

Opposites attract

A positive (+) charge pulls a negative (-) charge toward it.

Repel

When two positive charges or two negative charges push away from each other.

Neutral objects are attracted to charged objects

A charged object can pull in a neutral object because it rearranges the electrons inside the neutral object.

Neutral objects

Equal protons and electrons. Neutral objects can become charged through direct contact.

Conductors

Allow the free movement of electrons.

Insulators

Restrict or prevent electron movement.

Good Conductors

Copper, aluminum, gold (commonly used in wiring).

Fair Conductors

Graphite, silicon, salt water (limited electron movement).

Semiconductors

Have special properties that make them fair conductors, not good conductors. Technologies such as laser printing use conductors and insulators.

Technologies

Laser printing uses conductors and insulators.

Charging by Friction and Charging by Conduction:

Charging occurs when two neutral materials are rubbed together, transferring electrons between them.

Example: Rubbing a comb through hair.

Electrostatic Paint Sprayers

Use properties of static charges to more efficiently paint objects.

How electrostatic paint sprayers work

Paint particles are charged as they leave the sprayer. The object is then given the opposite charge.

How electrostatic paint sprayers work

What is a Metal Leaf Electroscope?

A tool used to detect electric charge.

How do Metal Leaf Electroscopes work?

Charging by induction and contact

Charging by Friction and Conduction: 

Charging occurs when two neutral materials are rubbed together, transferring electrons between them.

An example of charging by friction and conduction

Rubbing a comb through hair.

When do objects become easily charged?

In the winter, when the air is dry.

Dry air

allows charge to build up more easily

Humid air

contains water molecules that reduce charge buildup by transferring electrons away.

The impact of humidity on Charging

In dry air, a charged object has less chance of losing its charge.

The Electrostatic Series

A list of materials ranked by their tendency to gain or lose electrons. 

An example of the electrostatic series

If wool and rubber are rubbed together, wool loses electrons and becomes positive, while rubber gains electrons and becomes negative.

Acetate and Fur

Loses electrons easily

Rubber and telfon

Gains electrons most easily from other materials

Charging by conduction

The neutral object takes the same charge as the object it touches

Example of charging conduction

A negatively charged rod touches a sphere

Conduction between two charged objects

a positively charge object touches a less positively charged object, transferring electrons and balancing their charges.

Charging with induction

Objects can be charged without direct contact using a charged object.

When do induced charge separation happen?

Occurs when a charged object pulls or pushes electrons in a neutral object. Can be temporary or permanent.

Permanent charge by induction

To make the charge permanent, the neutral object is grounded.

First step of permanent charge by induction

a charged object is brought close to a neutral object

Second step of permanent charge by induction

The neutral object is grounded, allowing electrons to flow in or out.

third step of permanent charge by induction

Ground is removed leaving the object with a permanent charge

Electrical discharge

When a charged object loses excess charge, electrons move quickly from one to another.

Small electric discharge

Static shock

Large electrical discharge

lightning

Lightning rods

helps direct lightning safely to the ground