1. 7.2 Electric Current Current is the net movement of electric charges. – These can be electrons as in wires. – These can be ions as in electrolytes. In a circuit, electrons flow from negative terminal to positive terminal. – Thanks to Ben Franklin, “current flow” is the direction (+) charges flow. Since it isn’t (+)charges flowing in wires, the electron flow is opposite the “current flow”. – We will be using electron flow direction for current flow direction.

2. Electrons flow from the (+) terminal to the (-) terminal, whether that is a battery or an outlet.

3. Voltage difference-the force that pushes electrons. – Measured in volts (v) – Also known as potential or potential difference. Similar to the force of gravity pulling water from high potential energy to low potential energy, voltage difference causes electrons to flow from high potential to low potential.

4. Batteries-A source of voltage that produces a direct current. – Dry cell

5. – Wet cell

6. Resistance- the tendency of materials to resist the flow of charges. – Produces heat(like friction) – The heat can produce light – Resistance is measured in ohms(  – What affects the resistance of a material? Temperature-as temp. increases, so does resistance. Length- as the length or distance the electrons must travel increases, so does resistance. As the thickness of a wire increases, the resistance DECREASES.

7. Ohm’s Law

8. Example: Calculate the current in a circuit with 120 v of potential difference and a resistance of 24  Calculate the voltage through a circuit if the current is 6 amps and the resistance is 40 