Warm-up 1/30/18 First things first: make a new section in your journal for 2nd semester! At your table you will find 1 battery, 1 wire, and 1 light bulb.  Each person at your table must find a different way to light the light bulb.​ Sketch EACH of the ways your group found to light the bulb, and place the name of the person who successfully created the circuit that lit the bulb in that way.​ Describe what characteristics that each of your circuits shared.

Electric Conduction and Resistance Starting at page 180 Electric Conduction and Resistance

Electric Potential Difference Review from last unit: Electric fields… Caused by an electric potential difference Applies a force to a charged particle Causes (+) to move from high potential to low potential If WORK is done to the charged particle… Then it can be moved from low potential to high potential Potential difference (DV) = positive So…how does this relate to circuits?

Warm-up pt 2: In pairs, you will need 2 light bulbs, 1 battery, and 4 wires. Scenario 1: A: Light both light bulbs with the single battery (you may or may not need all wires). Sketch the configuration that successfully lit both bulbs. B. Light both light bulbs…but with a different configuration than you did in A. Sketch this new configuration. In this configuration, were the bulbs brighter, dimmer, or the same as in config. A?

Potential Difference (voltage) In a complete circuit, there must be a source of potential difference Electrons within the conductor must have some agent that applies a net force in order for them to have net movement in the conductor Potential Difference is synonymous with Voltage

What is necessary for a DC Circuit? a Complete Circuit has: A conducting pathway connecting two ends of … A Source of Potential Difference, Allowing current to flow through a… Resistive Electrical Component that consumes electrical power

What do mean by “Current”?

Electrical Conduction Best conductors = metals, typically Electrons are free to move among all metal atoms because of the nature of metallic bonding—there is a “sea” of electrons In a battery (cell), when the two terminals are connected with a conducting wire, there is an electric field produced within the wire and battery that applies a force to the electrons, causing them to move…

Drift Velocity The electrons in the battery “drift” towards the high positive potential end: Approximate magnitude vdrift= 10-4 m·s-1

Electric Current The flow of electrons through a conductor as a result of the application of a potential difference across the ends of the conductor Current = rate of flow of charge Fundamental Units = Ampere (1 A = 1 C·s-1)

Notes break! Time for a practice problem! Susie dries her hair in 10.0 minutes. What is the current flowing through her hair drier if it takes 6.00 x 103 C of charge to dry it in that time?

What Allows Current to Flow? What state of matter can have an electric current? ANY!! Charge Carriers = the part of the matter that allows the charge to be moved through a potential difference, causing a current Solids = free electrons in metals Liquids = Ions in molten and aqueous electrolytes Gases = electrons and + ions stripped from gas molecules by large potential differences

What is necessary for a DC Circuit? a Complete Circuit has: A conducting pathway connecting two ends of … A Source of Potential Difference, Allowing current to flow through a… Resistive Electrical Component that consumes electrical power Note: DC = direct current current always flows in the same direction

Conventional Current vs. Electron Flow Historically, the direction of the flow of charge carriers was defined to be from positive to negative It is now known that current is a flow of electrons from negative to positive, however… CONVENTIONAL CURRENT STILL IS DRAWN AND INTERPRETED AS FLOWING FROM POSITIVE TO NEGATIVE!

Conventional Current vs. Electron Flow

Can current ALWAYS flow freely?