Aim: How can we describe current? How do they work? STUDENTS DRAW Do Now: Make a bulb light with 1 wire & 1 battery. Draw your circuit!

How can we describe electricity? Electricity is a general term encompassing a variety of phenomena resulting from the presence and flow of electric charge (electrons). An electric current is produced when electrons collect on a surface (like a wire) and travel in a certain direction. Electrical currents can be seen in such things as lightning, static electricity, and the flow of electrical current in an electrical wire. Electrons have a negative (-) charge, moving (-) to (+). An electron is able to be removed (“jump”) from an object creating an electrical charge. An electrical current is simply the movement (transfer) of electron through a wire (circuit) e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e- e-

Defining Electric Current The rate at which charge passes a given point in a circuit. Higher current = more charge passing a given point each second. I = Q/t Units: Coulombs/Second = Amperes (A) Just like water flowing in a river! Path for a river is the river bed.

Example #1 The rate of current flow through a wire is 2.5 A over 4 min. How much charge & what number of electrons pass a given point? A

Envelope Activity Answer the following 2 questions involving current flow.

Envelope Activity 1. The current through a radio is 4.0 amperes. How many coulombs of electric charge passes through the radio is 1 minute? 2. The current traveling through an electric circuit is 62μA. How many electrons pass through the circuit in 2.0 seconds?

How can we describe a circuit? A circuit forms a closed path creating an electron current that allows electricity to flow. If the circuit is broken, electricity will not flow Show how circuit is drawn and circuit components.

Where did the energy come from to light the bulb? The energy to “PUSH” electrons comes from a battery. Potential Difference or voltage (V) Does this represent potential or kinetic energy? Explain.

How did the energy get from the battery to the light bulb? The wires allowed the energy or electricity to travel in the circuit. What prevented you from feeling the electricity? What do we call the rubber or plastic surrounding the wires? What are the wires made up of? Why?

Lithium Battery Why did this happen? What is the technical term for this?

Resistance Why is this a really bad idea? Almost unlimited current flow. Possible Fire! We need something to control or resist the current! A RESISTOR! What did your first circuit have that controlled current? Resistance: Property determining how much current will flow. Unit: Ohm (Ω) Symbol: R Skinny wire, long wire and increased temp have large resistance. Area, length, material and temperature all affect! Hall way

Summary What equation represents current? Explain how electrons flow in a circuit and their direction. What three variable make a circuit work?