Essential Questions:

What is electricity and how does it relate to energy?

What makes a circuit and what are the different types of circuits?

What is the relationship between voltage, resistance and current?

Electricity 101• Electricity is the flow of electrical charge

(electrons)

• Electricity is a secondary source (made from primary sources: coal, fuel, natural gas, oil…)

• Electricity is one of the most

widely used forms of energy.

Brainstorm….

Can you list 5 ways that you use electricity on a daily basis?

Electricity 101

• We tend to take electricity for granted, but electricity helps us in many ways

– Cooling/heating our homes

– Lighting our homes and school

– Powering television and appliances

– Charges our cell phones

Electricity 101• The flow of electrons through a closed

circuit.

What do you suppose happens to the electron flow when the circuit opens?

Two types of electricity

STATICCURRENT

StaticElectricity

Static Electricity• If you have ever been

shocked, you have experienced static electricity.

• Static electricity is the accumulation of excess electric charges on an object.

Static Electricity• There is a rule

associated with static electricity

• Opposite Charges Attract; Like Charges Repel

What Causes Static Electricity?• Most objects have a neutral charge

(equal numbers of protons and electrons)

• When one object rubs up against another object, electrons are transferredbetween the two objects and both objects become charged!

Building Up Charge• When an object becomes charged, the

charge is neither created or destroyed (Law of Conservation of Charge)

• Charge can only be transferred!!!

Examples of Static Electricity• Getting shocked when touching a metal door

knob

Examples of Static Electricity

• Hair standing up when rubbed with a balloon

Examples of Static Electricity• Clothes sticking together in the dryer

Build up of charges through

conduction- when objects touch

Lightning• Objects can transfer

electric charge (induction)

• When clouds form, they rub up against each other and become charged, opposite charges attract from the ground to the sky.

When a charged object gets near a

conductor

Static Electricity Explained

https://www.youtube.com/watch?v=yc2-363MIQs

Click for Video!

FrictionCharges that results by objects

rubbing against each other.

ConductionCharges that result by direct

contact.

InductionCharges that result by objects that do not come into contact.

Quick Activity

1. Blow up the balloon at your station. Rub this balloon against your hair/shirt. Is this transfer of e- an example of conduction, induction, or friction? Explain.

1. Turn on the faucet at your station so that the water flows in a steady stream. Take the charged balloon and slowly approach the stream of water. Is this phenomena an example of conduction, induction, or friction? Explain.

1. Now take the charged balloon and move it toward the tissue paper on your station. Is this phenomena an example of conduction, induction, or friction? Explain.

CurrentElectricity

Current Electricity– Current electricity is the flow of electrons through

a circuit.

– A circuit is a complete, closed pathway for electricity.

– Conductors allow electricity

to flow easily. (Ex. Copper)

Types of Current Electricity• Generators produce electric

current as a coil of wire moves through a magnetic field.

• As the coil rotates, the direction of the electric flow constantly reverses direction.

• This is called an alternatingcurrent (AC).

• AC is used to deliver power to houses, office buildings, etc.

Examples of AC Current

Most home appliances run on AC current.

Alternating Current

• Batteries can produce an electric current from chemical reactions.

• Electrons are produced from the chemical reaction inside the battery.

• Batteries produce direct current (DC) which flows in only one direction.

Types of Current Electricity

Direct Current

How do we get our electricity?• Research:

• Have you ever wondered why the lights turn on with just the flick of a switch?

• In groups of 2 or 3, research where our electricity comes from.

• Create an illustration/diagram that shows the path of electricity from its original source to a device that is powered by electricity.

• Be prepared to share with your classmates!

How do we get our electricity?

5

MeasuringElectricity

Measuring Electricity• Electricity can be measured a number of ways.

– Current

– Resistance

– Voltage

https://www.youtube.com/watch?v=8gvJzrjwjds

Click for Video!

Clipart Credits: http://www.sengpielaudio.com/calculator-ohmslaw.htm

Task:Use the

illustrationto create your

own descriptionsfor the terms:

VoltageCurrent

Resistance

currentvoltage

resistance

Current

• Electric current is very similar to a flowing river.

• With electricity, current (I) is a measure of the amount of electrons transferred over a period of time.

• The electrons move through conductive materials such as copper wire

• Amps is the unit for current

Voltage

• Voltage is the force that causes charges to flow. (Think about it as pressure)

• Unit: volts

Resistance

• Resistance is the tendency for a material to oppose the flow of electrons.

• Unit: ohms Ω

• Conductors have less resistance than insulators– Ex. Copper

Resistance will oppose electron flow through a conductor

Ohm’s Law• A formula used to measure resistance, current and/or

voltage.• Resistance is directly proportional to voltage &

inversely proportional to current– Resistance = voltage/current – Current = voltage/resistance– Voltage = current x resistance

Units

• Voltage = Volts

• Resistance= Ohms

• Current = amps

Flowing Electrons

• Ohm’s Law:

Example: What is the resistance of a circuit if the current is 4 amps and the voltage is 12 volts?

Answer: R=V/I = 12 V / 4 amps = 3 Ohms

Ohm’s Law PracticeComplete the Ohm’s Law practice problems.

PARALELL VS. SERIES

Series Circuit

• Only one path is provided for electric current.

Series Circuit

• In a series circuit, the voltage is divided amongst the load (assuming each bulb is the same wattage)

120 V

60 V60 V

What if a third bulb was added? A fourth?

Parallel Circuit

• Alternate paths or branches are provided for electric current.

Parallel Circuit

• In a parallel circuit, each load (bulb) gets the full voltage.

What if a fourth bulb was added?

120 V 120 V 120 V120 V

A circuit consists of a power source (like a battery), a conductive material (copper wire), and some object that needs to be powered (like a light bulb).

In this virtual lab activity, you will use your knowledge of circuits to follow a step of instructions to create circuits that will perform different tasks. As you complete each task, you will be directed to a new level.

Goal: Complete all levels in the circuit lab

Build a Circuit Virtual Lab Website:

http://thefusebox.northernpowergrid.com/page/circuitbuilder.cfm

Series and Parallel CircuitPractice

Complete the series and parallel circuits worksheet.