Chapter 7 section 2 Electric Current Electric Current - the net movement of electric charges in a single direction, measured in Amperes. The water molecules in this picture are all moving in one direction at a specific speed. We call the movement of the water molecules current. Electric charges can move in the same way. The charges move through wire like water flows in a waterfall.

Voltage Voltage - related to the force that causes electric charges to flow, measured in Volts. The reason why the water is flowing (current) in the previous picture is because gravity is pulling the water in one direction. Without that gravity, the water would be still like a pond (no current). Voltage is the reason the electric charges have current. Without voltage, electric charges will not move.

Electric Circuits Circuit - closed conducting loop through which an electric current can flow.

Resistance Resistance - tendency for a material to oppose electron flow and change electrical energy into thermal energy and light, measured in Ohms (Ω). When you connect a wire to both ends of a battery, the voltage of the battery moves the electrons (current). These electrons will move very fast because their is nothing to slow them down. When I add resistance to a circuit, it slows the current down. These are all resistors that are used in a circuit. They slow down the current in a specific part of a circuit.

Converting Electrical Energy into Other Forms Resistance is used to convert electrical energy into radiant and thermal energy. The kinetic energy of the electrons decrease with a resistor, which means that energy has to be turned into a different form of energy (conservation of energy). Radiant Energy Thermal Energy

Current in a Simple Circuit A simple circuit consists of: A source of voltage (battery) A conductor to connect the end of the battery (wire) A device that has resistance (light bulb) When the wires are connected to the battery, current flows through the wire. When the resistance of the lightbulb is present, electrical energy can be converted into radiant energy.

Ohm’s Law The flow of electrons (current) depends on how much push is provided (voltage) and how much they are slowed down by a device (resistance). This relationship is called Ohm’s Law: I - Current (unit: Amps) V - Voltage (unit: Volts) R - Resistance (unit: Ohms)

Summary Electric current is the net movement of electric charge in a single direction. A voltage difference is related to the force that causes charge to flow. A circuit is a closed, conducting path. Resistance is the tendency of a material to oppose the flow of electrons. Ohm’s Law relates the current (I), resistance (R), and voltage (V) in a circuit.