EGR nd Hour Agenda Teaming Batteries Introduction to Ohms Law

EGR 1012 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”

EGR 1013 Code of Collaboration Every team member is responsible for the team’s progress and success! –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

EGR 1014 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

EGR 1015 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

EGR 1016 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.

EGR 1017 Circuit Components Batteries + +

EGR 1018 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

EGR 1019 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).

EGR Current Direction We will adopt “Conventional Flow” for all of our work!

EGR 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

EGR 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.

EGR When batteries are connected with their polarities in the same direction, they are in a series-aiding arrangement.

EGR When batteries are connected with their polarities in the opposite direction, they are in a series-opposing arrangement.

EGR In Class Activity What is the total voltage between terminals A and B in the figure below? Which terminal is at a higher potential? 9V4V15V AB

EGR Introduction to Ohm’s Law A 1 Ohm resistance limits the current to 1 Amp when 1 Volt is applied. V = I. R

EGR Ohm’s Law Three forms: Use the form that best describes the quantity that you are trying to determine

EGR Determine the Current + _ I

EGR Determine the Voltage + _

EGR Determine the Resistance + _