Transcript Today`s Agenda

2nd Hour Agenda
Teaming
Batteries
Introduction to Ohms Law
EGR 101
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Collaborative Learning
• Positive Interdependence
– Share responsibilities (sink or swim together)
– Be sure that all team members learn the
material
• Your success is linked to the success of your
teammates
– Involve each team member
• Each team member’s efforts are required for
success
• No “free riders”
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Code of Collaboration
• Every team member is responsible for the
team’s progress and success!
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Attend all classes and team meetings
Be on time
Come prepared
Carry out assignments on schedule
Be an active listener
Listen to and show respect for the contributions of the
other team members
• Constructively criticize ideas, not people
• Resolve conflicts and avoid disruptive behavior
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Code of Collaboration
• Avoid disruptive side conversations
– Only one person speaks at a time
• Everyone participates, no one dominates
• Be brief and to the point
– Avoid long anecdotes and examples
• Set a norm for behavior
– “Code of Conduct” for your team
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Out-of-Class Team Activity
• Work together to develop your own team’s
Code of Conduct
– What do you expect of each other?
Make your expectations explicit (like attending
all meetings, arriving on time, prepared, etc)
– What are the consequences if someone fails
to meet expectations?
• Due at the beginning of class next
Tuesday
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Where Does Current Come
From?
• The free electrons in a conductor need to
be replaced when they move through the
conducting medium (the wire).
• These electrons are replaced by electrons
from a source of energy such as a battery.
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Circuit Components
• Batteries
+
+
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Source of Voltage in a Battery
• A chemical reaction within the battery
separates positive and negative ions
(charged atoms)
• When the battery is connected to a circuit,
the negative charge move toward the
positive charge and a current is produced
• The amount of current is constrained by
the resistance of the circuit
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Example of A Battery
The source of energy E in (Joules) releases charges Q in
(Coulombs)
Voltage (V) – the difference in potential that uses E = one
Joule (J) of energy to move a charge Q = one coulomb (C).
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Current Direction
We will adopt “Conventional Flow” for all of our work!
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Mathematical Relation
• E: Energy required to move charges in
Joules (J).
• Q: Charge value in Coulombs (C).
• V: Voltage or potential difference across
the battery's posts in volts (V).
•
Thus, V = E / Q.
• In units: 1 Volt = 1 Joule/Coulomb
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Team In-class Activity (15 minutes)
• A 10 V source uses 2 Joules of energy per
second. Calculate the current being used
by the source.
• Hint, turn the word problem into equations;
write down what you know.
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When batteries are
connected with their
polarities in the same
direction, they are in a
series-aiding
arrangement.
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When batteries are
connected with their
polarities in the
opposite direction,
they are in a
series-opposing
arrangement.
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In Class Activity
• What is the total voltage between
terminals A and B in the figure below?
A
B
9V
4V
15V
Which terminal is at a higher potential?
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Introduction to Ohm’s Law
• A 1 Ohm resistance limits the current to
1 Amp when 1 Volt is applied.
V = I.R
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Ohm’s Law
V  IR
• Three forms:
• Use the form that best
describes the quantity
that you are trying to
determine
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V
I 
R
V
R 
I
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Determine the Current
I
+
_
V
I 
R
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Determine the Voltage
+
_
V  IR 
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Determine the Resistance
+
_
V
R 
I
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