Download Current

Unit 6 Section 2 Notes
Static Electricity
 The
build-up of an electric charge
on the surface of an object.
 The charge builds up but does
not flow.
 Static electricity is potential
energy. It does not move. It is
stored.
Current Electricity
 Current:
The flow of electrons from
one place to another.
 Measured in amperes; Abbreviated
amps (A)
 Current electricity is Kinetic energy
What is an Ampere?

Ampere: a measurement of the
current flow rate of electrons.
 Basically, the larger the size of wire, the
greater the ampere capacity.

Where do your see these plugs?
 Why are they larger?
Copyright © 2010 Ryan P. Murphy

Answer: The Plug to a dryer or stove is
much thicker than a standard outlet to
account for extra amps.
Copyright © 2010 Ryan P. Murphy

Answer: The Plug to a dryer or stove is
much thicker than a standard outlet to
account for extra amps.
Copyright © 2010 Ryan P. Murphy
How can we control currents?
With
circuits.
Circuit: is a path for the
flow of electrons. We use
wires.
There are 2 types of currents:
Current (DC) – Where
electrons flow in the same direction in
a wire.
 Direct
 Example: Batteries , Static Electricity,
Lightning
There are 2 types of currents:
Current (AC) – electrons
flow in different directions in a wire;
flow is back and forth, changing its
direction many times in one second.
 Alternating
 Example: Plugs and outlets
Advantages of AC
Voltage can be raised or lowered.
 More efficient over long distances.

Rockin Quiz!
This is your chance to rock it out in science class so
don’t just sit there. At least rock your head or tap
your desk etc.
After some intro slides, teacher will call on a student
to rock it out on their way to the board.
Student goes to board and touches the picture that
represents AC or DC on the AC/DC logo (If using a
screen just point and drum the air).
Student will then pick a new student to go to the
board as the teacher changes the slide.
Thunderstruck video (For the music during quiz and I
didn’t see anything inappropriate ).
http://www.youtube.com/watch?v=v2AC41dglnM

Note: Many devices such as computers plug
into the wall (AC Current) but the AC current is
converted into DC Current to run through the
machine.
 For simplicity sake in this activity, if it has a plug we
will call it AC, and if doesn’t (batteries) we will call it
DC.
“DC”
“Its one way!”
“AC”
“It Alternates!”

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?
?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

Is this (AC) Alternating Current, or (DC)
Direct Current?

What is Resistance??? This... ???
What is Resistance?
 The
opposition to the flow of an
electric current, producing heat;
caused by internal friction
 The greater the resistance, the
less current gets through.
 Good conductors have low
resistance.
 Measured in Ohms; Symbol:
The refusal to accept
or comply with
something; the attempt
to prevent something
by action or argument.
What Influences Resistance?
of wire – aluminum and
copper have low resistance
 Thickness – the thicker the wire
the lower the resistance
 Length – shorter wire has lower
resistance
 Temperature – lower temperature
has lower resistance
 Material
What is Voltage?

Volt: A measure of the force or
pressure under which electricity flows.
 The greater the voltage, the greater
the force or “pressure” that drives the
charge through the circuit.

Electricity flows through a wire much like water
flows through a pipe.

Electricity flows through a wire much like water
flows through a pipe.
 A force is required to drive it and resistance to is
encountered, the flow of current is measured in amps
Difference between Volts and
Amps
 Example
– you could say
that…
 Amps measure how much water
comes out of a hose.
 Volts measure how hard the
water comes out of a hose.
What are Watts?
 Watt:
is a measurement of electrical
power created.
 1 watt is equal to one joule of energy per
second
What are Watts?
 A Watt
is calculated by multiplying
volts times amps.
 Most household electrical usage is
billed in kilowatt hours, or the amount
of hours times 1,000 watts.
• Volts are a measure of the force or pressure
under which electricity flows.
• Amps are a measurement of the current flow
rate of electrons
• Resistance:
Anything in an electrical
circuit that impedes the flow of current is
referred to as resistance.
• Watts is a measurement of electrical power
created.
– 1 watt is equal to one joule of energy per second.
• Volts are a measure of the force or pressure
under which electricity flows.
• Amps are a measurement of the current flow
rate of electrons
• Resistance:
Anything in an electrical
circuit that impedes the flow of current is
referred to as resistance.
• Watts is a measurement of electrical power
created.
– 1 watt is equal to one joule of energy per second.
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measurement
of the current
flow rate of
electrons
This is a
measure of
the force or
pressure under
which
electricity
flows
Which is the correct description of Watts?
This is a
measurement
of electrical
power
created.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
Anything in
an electrical
circuit that
impedes the
flow of
current.
• Volts are a measure of the force or pressure
under which electricity flows.
• Amps are a measurement of the current flow
rate of electrons
• Resistance:
Anything in an electrical
circuit that impedes the flow of current is
referred to as resistance.
• Watts is a measurement of electrical power
created.
– 1 watt is equal to one joule of energy per second.
• Volts are a measure of the force or pressure
under which electricity flows.
• Amps are a measurement of the current flow
rate of electrons
• Resistance:
Anything in an electrical
circuit that impedes the flow of current is
referred to as resistance.
• Watts is a measurement of electrical power
created.
– 1 watt is equal to one joule of energy per second.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement of
electrical power
created.
Which is the correct description of Watts?
Anything in
an electrical
circuit that
impedes the
flow of
current.
This is a
measure of
the force or
pressure
under which
electricity
flows
This is a
measurement
of the current
flow rate of
electrons
This is a
measurement
of electrical
power created.

Georg Simon Ohm (1789 –1854)
 Ohm found that there is a direct proportionality
between voltage applied across a conductor and
the resultant electric current.
Learn more at..
http://www.allaboutcircuits.co
m/vol_1/chpt_2/1.html

Ohms: The measure of resistance in a circuit
to the flow of an electric current.
 The greater the ohm value the more difficult it is for
current to flow through a given circuit.
 A low ohm value represents a low resistance and
the easy flow of current through a circuit
Current

Ohms: The measure of resistance in a circuit
to the flow of an electric current.
 The greater the ohm value the more difficult it is for
current to flow through a given circuit.
 A low ohm value represents a low resistance and
the easy flow of current through a circuit.

Ohms Law Simulator at…
 http://phet.colorado.edu/en/simulation/ohms-law

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?
V
R= -----I
220 V

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?
V
220 V
R= ------ --------- =
I
36 A

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?
V
220
R= ------ --------- = 6.1 ohms
I
36A

If 220 volts travel through a copper wire and
the current is 36A,
 What’s the resistance of the wire?
V
220
R= ------ --------- = 6.1 ohms
I
36A

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?
V
I = ----R
120 V
----------- = .0024A
50,000 ohms

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?
V
I = ----R
120 V
----------- = .0024A

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?
V
I = ----R
120 V
----------- = .0024A
50,000 ohms

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?
V
I = ----R
120 V
----------- = .0024A
50,000 ohms

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?
V
I = ----R
120 V
----------- = .0024A
50,000 ohms

A Rude Monkey decided to stick his tongue to a
120 V outlet with 50,000 ohms of resistance.
 How much current will he experience?
V
I = ----R
120 V
----------- = .0024A
50,000 ohms

Video Link! Current, Voltage, Resistance
 http://www.youtube.com/watch?v=J4Vq-xHqUo8