Controlling the Flow of Electrical Current Section 2.1-Day #1

Review A 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 Plan Discussion on controlling the use of electricity, video clips, discussion on insulators and conductors, animations, and an activity. I can identify electrical conductors and insulators.

Review Conductors allow movement of electricity. Insulators oppose movement of electricity. Resistors allow for some current (some movement) to get through, but not all.  Copper is a conductor.  Plastic is an insulator.  Tungsten is a resistor.

Review An 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) html

Periodic Table Which elements conduct electricity? Which don’t? Generally, metals are conductors and non-metals are insulators.

The Controlled Use of Electricity

Neon Neon can be used as a circuit, but needs the following: 1.Electricity must flow through the whole tube 2.There must be an on and off switch. 3.The whole thing must be contained to protect people.

A Unique Circuit Neon signs are unique because they have a circuit made of gas (neon) instead of wires.

Neon Signs The type of gas determines the color of the sign.

How Do Neon Signs Work?

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

Conductors and Insulators

Conductors, Insulators and In-Between All substances can be put into 4 groups depending on how well they pass on electricity.

Insulators Don’t allow charges to transfer. Electrons are tightly bound to the positive nucleus of their atoms. E.g., Rubber US/Pages/product.aspx?category=linemen_gloves_low_vol tage&cat=HLS-HES&pid=class_00_14inch_gloves

How can squirrels safely walk on high voltage wires? The wires are well insulated.

Have You Ever Noticed? Where the wires are attached to utility poles sometimes there are glass bell- shaped objects? sulators_green,yellow.pdf

Semi-Conductors Allows 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

Conductors Do allow charges to transfer. Do 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 Conductors InsulatorsConductors GlassCopper plasticAluminum AirSilver WoodGold RubberThe human body

Super-Conductors Allows 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-Conductors Used in generators and high voltage power lines

Powerful Electromagnets The most important use of superconductors is for making powerful electromagnets. mri-can-lift-a-tank-like-magneto-or-see-deep-into-your-brain

My Brain Large cerebellum-good for coordination and balance.

What We Learned Today I 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.

Homework Check 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 Insulators Conductors and Insulators