Download Controlling the Flow of Electrical Current

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)

http://www.autoshop101.com/trainmodules/elec_circuits/circ
104.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.
http://amanartsprint.com/led-board-neon-sign-board/
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
https://www.salisburybyhoneywell.com/enUS/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 bellshaped objects?
http://www.cccsd.org/webpages/chathaway/files/conductors%20and%20in
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.

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
Insulators
Conductors
Glass
Copper
plastic
Aluminum
Air
Silver
Wood
Gold
Rubber
The 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
http://www.forbes.com/fdc/welcome_mjx.shtml
Powerful Electromagnets

The most
important use of
superconductors
is for making
powerful
electromagnets.
http://www.extremetech.com/extreme/169526-worlds-most-powerfulmri-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