Electric Current Chapter 7 section 2

Electric Current Electric current- The flow of electrons through a wire or any conductor. Measured in units of Amperes (A) Charges flow from High voltage to Low voltage Voltage difference- push that causes charges to move- measured in volts (V) For charges to flow, the wire must always be connected in a closed path, or circuit http://www.school-for-champions.com/science/dc.htm

Resistance Resistance- the tendency for a material to oppose the flow of electrons, changing electrical energy into Thermal energy and light Resistance is measured in Ohms (Ω) Making wires thinner, longer, or hotter increases the resistance Ohm’s Law- the current in a circuit equals the voltage difference divided by the resistance I = V/R

Electrical Circuits Less resistance means less heat, which is safer for use in your home As resistance increases, current decreases As voltage difference increases, current increases

Sources of Electricity A Dry Cell battery produces a voltage difference between its zinc container and its carbon suspension rod, causing current to flow between them.

Sources of Electricity A Wet Cell battery contains two connected plates made of different metals in a conducting solution- like a car battery Electrical Outlets- have a voltage difference across the two holes of an electrical outlet and a generator at a power plant provides the voltage difference Resistance- the tendency for a material to oppose the flow of electrons, changing electrical energy into Thermal energy and light

Electrical Circuits Series circuit- current has only one path to flow through Parallel circuit- current has more than one path to flow through Magnetic fields form around wires through which electricity is moving Electromagnet- a temporary magnet made by placing a piece of iron inside a current-carrying loop of wire More loops = stronger More voltage = stronger Only works for DC current