Lesson 3

1 What did you do last time? 2 battery series electrons volts voltage charge PRINT the word next
to the image on the next slide.
Electronics1 - L3 vol vol ele cha ser bat

4 You can now measure a battery’s voltage,
but WHAT makes a battery, a battery?
To find out, let’s make a battery!
LED scissors
aluminum foil
3 clean pennies
(soak in vinegar
to clean)
test leads multimeter You will need these
items from your kit.
The Voltaic Pile You will need these other
items from your home.
3 galvanized
(zinc coated)
vinegar poured
into a small cup
with a sprinkle
of salt added
5 Use a penny
to draw
three circles
on the paper.

Cut out the
paper circles.
Stack one cell
or “element”
in this sequence:
Cut out a 2 x 2 inch (5 x 5cm)
square of aluminum foil,
which will become
the base.
Use the multimeter
to measure and record
the voltage of this one element.
1 2 3 4 1 element 1 galvanized washer

1 circle of paper
dipped in vinegar
(damp, not too wet)
This is the electrolyte.

1 copper penny
NOTE: The circles
do not have to be
too precise.
6 Continue to add more elements
in sequence to your stack.
Measure and record
the voltage as you add
more elements.
Clearly this VOLTAIC PILE generates enough voltage to light an LED.

NOTE: Some metal combinations make stronger batteries than others.
Connect an LED to the voltaic pile. The longer positive lead must touch the copper penny or foil base. element 2 element 1 element 3 5 6 Does the voltage
pile light the LED
What are the three
layers in each element
7 The voltaic pile, invented
by Alessandro Volta in 1800,
was the first electric battery.
Its invention can be traced back
to a once-famous argument between
Volta and Luigi Galvani, a fellow scientist
who had gained notoriety
for his experiments on frog legs.

In 1780, Luigi Galvani was dissecting
a frog affixed to a brass hook.
When he touched the frog’s leg
with his iron scalpel, the frog’s leg twitched!

As you might imagine, it was quite startling.
Galvani believed the energy that drove
this contraction came from the leg itself.
He called it "animal electricity.”
Luigi Galvani
8 Alessandro Volta disagreed
with his friend’s conclusions.
He argued that the “electric”
phenomenon was caused
by the two different metals,
the brass hook and the iron scalpel,
being joined together by a moist
intermediary, the frog’s leg.

Volta set out to prove his hypothesis.

Volta did not use the frog’s leg.
Instead, he substituted a simple piece
of cloth soaked in brine (an electrolyte)
to separate a brass hook from an iron scalpel.
The completed “voltage pile” produced a voltage.
This proved that the frog’s leg was not necessary.
Alessandro Volta
9 Volta then tested other metals. By stacking pairs of
copper and zinc discs with an electrolyte between them,
Volta could increase the amount of electricity produced.

The result was what we call a voltaic pile, one of the first devices to provide a reliable source of electricity.
A pile, however, generated only a limited voltage. Several piles — a “battery” of them — could be assembled side by side and connected to each other with metal strips to create a higher-powered energy source.

Volta gave his name to the measurement for electrical energy, the “volt.” With his discoveries, electricity went from being the parlor tricks of static electricity to becoming a major new source of energy.
Volta showed that his wet stack of “dissimilar metals” not only created a small electrical current, but also that the current could be drawn off through wires and used for experiments. from Wikipedia The Voltaic Pile
10 Galvani 11 Volta and the First Battery 12 ELECTRICAL You have measured voltage with your multimeter and
you know how to generate voltage with a voltaic pile.

WHAT IS voltage?
What are you measuring and generating?

You can think of voltage as . . .
13 The yellow character
the electron(s) THROUGH the wire.

This character symbolizes
electrical PRESSURE.
14 Voltage is the pressure from an electrical circuit’s power source.

The electrical PRESSURE
in DC circuits comes from a constant
voltage source such as battery.
The electrical PRESSURE for AC circuits
comes from a wall plug.

Voltage pushes electrons
(the very pink Mr. Amp) through a wire.
Electrical PRESSURE transfers energy
to circuit components --
allowing a motor to spin,
a buzzer to BUZZ
or an LED to light.
15 A well-known analogy
for voltage is the water hose.

In this analogy, you can imagine
voltage as being like water pressure.
a battery pushing electrons
through a wire.
The water pressure supplied
by a faucet being turned ON
is analogous to
Turning on the faucet pushes water through a garden hose. The battery
connected to
a circuit loop
pushes electrons
(current) through
a wire.
16 Voltage
is electrical pressure.
Just as water pressure pushes water through a hose,
so electrical pressure from the battery
pushes electrons through this circuit.
Let's say that again!
17 When a battery is NOT connected to a circuit,
it has the POTENTIAL to do work.
It is like a rock resting precariously at the top of a hill.

Some action is required
to transfer the stored energy
into another form of energy.

The POTENTIAL difference in voltage
between the battery’s two terminals
creates an electrical PRESSURE
which is measured in volts.

to force electrons
to flow as current
when the battery
is connected to a circuit.
18 Simple Water Analogy Voltage - What is it? 19 What is voltage What was the first battery called In copper wires
in a circuit, which
particles are able to flow
Is electrical current
involved in controlling
muscle contractions
1 2 3 4 5 In a hose connected
to a faucet, what part would be analogous
to a voltage source
YES! electrical pressure voltaic pile the faucet electrons