ELECTRICITY SPS10. Students will investigate the

properties of electricity and magnetism.

a. Investigate static electricity in terms of

• Friction

• Induction

• Conduction

b. Explain the flow of electrons in terms of

• Alternating & direct current

• The relationship among voltage, resistance and current

• Simple series & parallel circuits

Overview ELECTRICITY

Static Electricity Circuits Currents Voltage Resistance

Direct

Alternating

Series

Parallel

Induction

Conduction

Friction

Essential Questions

• What does it mean when something is electrically charged?

• How can objects become electrically charged? • Why can small birds sit on high-voltage power lines? • What characteristics of material make it a good

conductor or insulator? • Why are insulators attracted to charged objects? • Why are alternating currents commonly used in

household applications?

We Take It For Granted!

• Look around the room… • How many objects, devices or appliances

require electricity? • Think about your homes….how many things

require electricity? • What happens when there’s a power outage? • Our lives are put on hold! Why? • We are extremely dependent on

ELECTRICITY!

Electricity Origins?

• Where does it come from? • Power plants • Who makes it? • Nobody! It is not made…it’s converted! • How is it converted? • The force of steam is converted into mechanical

energy which causes a turbine (a huge wheel thingy) to rotate. The turbine is connected to an electrical generator that produces current (electricity).

• How does it get to your home/school? • It travels along wires to your home/school.

Static Electricity • What happens when you drag your feet on

carpet and then touch a doorknob? • You get a SHOCK! • Why? • Walking across the carpet causes electrons to

leave the carpet and enter your body. • When you touch the metal handle, the extra

electrons jumped from your hand to the metal. • When the electrons move from one place to

another, energy is transferred.

Transfer of Electric Charge

• Static electricity charges can build up in three ways: – _________________ – _________________ – _________________

Transfer of Electric Charge

• Charging by _______________ is the acquiring of charges when an object that has an opposite charge is ___________.

• Charging by _______________ is the acquiring of charges by _____________. If a charged object touches a neutral object, ____________ are ______________.

• Charging by _______________ is the acquiring of charges by having objects ___________ across each other.

Electric Current • The ____________ of __________ from one

place to another is called _________________. • Electric current is measured in _____________. • An ampere tell us how much current is moving

past a point in a circuit in one second. • One ampere is equal to __________ electrons

per second. • Ampere may be shortened and called the ____.

Circuits • When electrons travel in a current, the

path they follow is called a ___________. • The circuit begins at the power source to

the _______ and back to the power source.

• If the circuit is unbroken, it is _________ • If the circuit broken, it is ________.

CLOSED OPEN

How To Draw A Circuit

• Cell (power source)

• Wiring

• Closed switch

• Open switch

• Bulb

Conductors & Insulators

• Let’s remember…. • Conductors conduct electricity: _______ • Insulators don’t: __________________ • Not all conductors allow electricity to pass

through them in the same way. • Not all insulators slow down electricity in

the same way

Resistance • A measure of how hard or how easy it is for

electric current to flow through a material. • Measured in _______. • Causes electrical energy to change into ______

and _________ energy. • Depends on three things

– _____________ – _____________ – _____________

Resistance

• Example: Think of 2 water hoses. One has a larger opening in the middle. If a pump is pumping water at the same rate through both hoses, which one will produce more water in one minute?

• The hose with the larger opening. • Conductors have low ____________. • Insulators have high _____________.

Resistance

• Can be calculated • voltage/current • Voltage is the energy that a power source

gives to the electrons in a circuit

More on Circuits

• Circuits can be in a ________ or __________. • Series circuits have a power supply (battery)

and wire, but they contain multiple electrical devices.

• Example: decorative lights • What happens on some strings when one bulb

blows? • If the entire string of lights stops working, you

have a series circuit.

Parallel Circuits

• Parallel circuits have more than one path for the current to follow.

• Homes are mostly wired this way. • If you have a string of decorative lights, if

one blows, the others will remain lit.

Fuses

• Provide safety for circuits to prevent fires • Fuses have metal on top that melts if it

gets too hot. When it melts, the circuit is broken. What happens when a circuit is broken?

• It stops transporting electricity.

Circuit Breakers

• Are also safety devices to prevent fires • When they get too hot, they switch

themselves off or open the circuit. • What happens when a circuit is open? • It stops working! • Circuit breakers can be reset

Currents

• AC: ___________________________ (the current can flow more than one way)

• DC: ___________________________ (current can only flow one way)

• AC is what we have in our homes. • DC is what batteries offer.

Let’s Review

• Electricity is the flow of electrons • Static electricity is a buildup of electric

charge • The charges can build up by induction,

friction or conduction • Current, the rate of flow of electricity, is

measured in amperes. • A closed circuit is complete & unbroken • An open circuit is incomplete & broken

Review

• Drawings of circuits are called schematics • Resistance measures how easily

electricity flows through a material