Controlling the Flow of Controlling the Flow of Electrical CurrentElectrical Current

Section 2.1-Day #1

ReviewReviewA car designer has proposed a new car battery. She is planning to test the following different electrode combinations: a) both zinc b) zinc and copper c) both copper, d) zinc and carbon e) both carbon. Will all of these combinations work? Explain why or why not.

The PlanThe PlanDiscussion on controlling the use

of electricity, video clips, discussion on insulators and conductors, animations, and an activity.

I can identify electrical conductors and insulators.

ReviewReview

ReviewReviewAn electrical circuit is a

system made up of four subsystems:

1.Source (e.g., cell or battery)

2.Conductor (e.g., wire)3.Control (e.g., switch)4.Load (e.g., lamp/motor)

http://www.autoshop101.com/trainmodules/elec_circuits/circ104.html

Periodic TablePeriodic TableWhich elements conduct

electricity? Which don’t?

Generally, metals are conductors and non-metals are insulators.

The Controlled Use of The Controlled Use of ElectricityElectricity

NeonNeonNeon can be used as a circuit,

but needs the following:1. Electricity must flow through

the whole tube2. There must be an on and off

switch.3. The whole thing must be

contained to protect people.

A Unique CircuitA Unique CircuitNeon signs are unique because

they have a circuit made of gas (neon) instead of wires.

Neon SignsNeon Signs The type of gas determines the

color of the sign.

http://amanartsprint.com/led-board-neon-sign-board/

How Do Neon Signs Work?How Do Neon Signs Work?

How Do Neon Signs Work?How Do Neon Signs Work?

Conductors and InsulatorsConductors and Insulators

Conductors, Insulators andConductors, Insulators and In-Between In-Between

All substances can be put into 4 groups depending on how well they pass on electricity.

InsulatorsInsulatorsDon’t allow charges to

transfer.

Electrons are tightly bound to the positive nucleus of their atoms.

E.g., Rubberhttps://www.salisburybyhoneywell.com/en-US/

Pages/product.aspx?category=linemen_gloves_low_voltage&cat=HL

S-HES&pid=class_00_14inch_gloves

How can squirrels safely walk on high voltage wires?

The wires are well insulated.

Have You Ever Noticed?Have You Ever Noticed?Where the

wires are attached to utility poles sometimes there are glass bell-shaped objects?

http://www.cccsd.org/webpages/chathaway/files/conductors%20and%20insulators_green,yellow.pdf

Semi-ConductorsSemi-ConductorsAllows charge transfer under some

conditions.

Electrons are not tightly bound and flow in the direction of the positive terminal. They can conduct a current, but needs electricity.

Good at controlling electrical currents.

E.g., silicon and gallium

ConductorsConductorsDo allow charges to transfer.

Electrons are not tightly bound, but flow in any direction. Electric current can flow freely.

Most conductors have some resistance to the flow of electrons.

E.g., Metals

Isolators vs ConductorsIsolators vs Conductors

Insulators Conductors

Glass Copper

plastic Aluminum

Air Silver

Wood Gold

Rubber The human body

Super-ConductorsSuper-ConductorsAllows charges to transfer very easily (excellent

conductors).

Perfect conductors, for they are substances with no resistance to electron flow.

They are usually created by lowering the temperature of the conductor.

Super-ConductorsSuper-ConductorsUsed in generators and high

voltage power lines

http://www.forbes.com/fdc/welcome_mjx.shtml

Powerful ElectromagnetsPowerful ElectromagnetsThe most

important use of superconductors is for making powerful electromagnets.

http://www.extremetech.com/extreme/169526-worlds-most-powerful-mri-can-lift-a-tank-like-magneto-or-see-

deep-into-your-brain

My BrainMy Brain

Large cerebellum-good for coordination and balance.

What We Learned TodayWhat We Learned TodayI can identify electrical conductors and insulators.

What is the difference between a conductor and an insulator?

Conductors allow current to flow easily; insulators do not.

HomeworkHomeworkCheck and Reflect #5 and 7 (p. 303).

5. Conductivity is related a substance’s atomic structure. Conductors allow electrons to flow, while insulators do not allow electrons to flow freely.

7. Metal A provides more resistance to current flow.

Conductors and InsulatorsConductors and Insulators