Transcript ELECTRICITY 1 2 3 - Stillwater Christian School

ELECTRICITY TOPIC #1
IMPORTANT TERMS TO KNOW
1. breadboard: circuit board on which electrical
components are attached
2. conducting: (material that) serves as a
channel for electricity
3. terminals: point where electiric current
enters or leaves
4. insulation: prevents/restricts flow of
electricity
5. electricity: flow of electrons
6. series: one end to end connection of
electrical components
7. Current: flow of electricity
8. battery: storage of electricity
9. filament: thread-like conductor that lights up
when current flows through it
10. circuit: complete path of an electrical
current
11. parallel: two electrical components in the
same path
What happens to the voltage when you
connect a set of batteries together in a
series?
What happens to the voltage when you
connect a set of batteries together in a
series?
The voltage of
the batteries
combines
increasing the
total voltage
1.5 volts
+1.5 volts
3.0 volts
The figure, below, illustrates a battery pack in which “cell 3”
produces only 0.6V instead of the full 1.20V. With depressed
operating voltage, this battery reaches the end-of-discharge point
sooner than a normal pack. The voltage collapses and the device
turns off with “Low Battery” message.
The figure, below, illustrates four cells connected in parallel.
The voltage of the pack of 4 batteries remains at 1.20V, but the
current handling and runtime are increased fourfold because
when batteries are connected in parallel the current gets
divided between the two batteries and so the runtime will
increase.
A weak cell will not affect the voltage but will provide a low
runtime due to reduced current handling. A shorted cell could
cause excessive heat and become a fire hazard.
ELECTRICITY TOPIC #2:
Identifying Resistors and using Ohm’s Law
I = E/R
“I” stands for
I = E/R
“I” stands for current
I = E/R
“I” stands for current
“E” stands for
I = E/R
“I” stands for current
“E” stands for volts
I = E/R
“I” stands for current
“E” stands for volts
“R” stands for
I = E/R
“I” stands for current
“E” stands for volts
“R” stands for resistance
• The ampere (symbol: A) is the SI unit of
electric current[1] (symbol: I) and is one of the
seven[2] SI base units. It is named after AndréMarie Ampère (1775–1836), French
mathematician and physicist, considered the
father of electrodynamics. In practice, its
name is often shortened to amp.
• In practical terms, the ampere is a measure of
the amount of electric charge passing a point
per unit time. Around 6.241 × 1018 electrons
passing a given point each second constitutes
one ampere.[3]
What is a volt, by the way?
A volt is the international scientific term used to
describe the electric force of a battery (a.k.a. the
electromotive force).
Volts are determined by finding the potential
energy that would be released when one ampere
of current is positioned against one ohm of
resistance.
ELECTRICITY TOPIC #3:
Resistors in Series and Parallel circuits
In a series circuit you would add
the total resistance and divide it
into the total voltage
Series
Circuit
With One
Resistor
Series
Circuit
With One
Resistor
3 amps
What if you had more than one
resistor, though?
Series
Circuit
With Three
Resistors
Series
Circuit
With Three
Resistors
Series
Circuit
With Three
Resistors
(0.5 amps)
In a parallel circuit you would add
the reciprocals of all the resistors
and divide that total into the
number 1. Then you would take
this answer and divide it into the
total voltage
????
1/10 + 1/2 + 1/1 =
1/10 + 5/10 + 10/10 = 16/10 = 8/5
SO…..
1/10 + 1/2 + 1/1 =
1/10 + 5/10 + 10/10 = 16/10 = 8/5
SO…..
1 divided by 8/5 =
1/1 times 5/8 = 5/8 = .625
FINALLY…..
1/10 + 1/2 + 1/1 =
1/10 + 5/10 + 10/10 = 16/10 = 8/5
SO…..
1 divided by 8/5 =
1/1 times 5/8 = 5/8 = .625
FINALLY…..
9 divided by .625 = 14.4 amps
How about a more simpler way for
our sixth grade class?
For the sixth grade we’ll use all the same ohm
resistors. This is the only condition under
which this “trick” will work, though.
Let’s say we had a circuit with 50 volts and two 5
ohm resistors.
For the sixth grade we’ll use all the same ohm
resistors. This is the only condition under
which this “trick” will work, though.
Let’s say we had a circuit with 50 volts and two 5
ohm resistors.
Divide resistor value by the number of resistors
in the circuit. Then divide the total voltage by
this quotient.
For the sixth grade we’ll use all the same ohm
resistors. This is the only condition under
which this “trick” will work, though.
Let’s say we had a circuit with 50 volts and two 5
ohm resistors.
Divide resistor value by the number of resistors
in the circuit. Then divide the total voltage by
this quotient.
5 ohms divided by 2 resistors equals 2.5
50 divided by 2.5 equals 20 amps
Electrical Fuse Lab