Chapter 10 Current Electricity 10.1 - Electricity and Electric Circuits Current Electricity - electric charges flowing in a circuit through a conductor in a controlled way The parts of an electric circuit Energy source ex: battery Load ex: light bulb Switch ex: on/off switch Wires ex: completes the path and joins everything together Energy Sources of Circuits Energy is measured in JOULES (J) Electrical energy is provided by electrons Sources of Electrical Energy Electric cell - converts chemical energy into electrical energy (battery) Two kinds: Primary Cells and Secondary Cells Primary cells can’t be recharge; Secondary cells can be recharged The Load in Circuits Converts electrical energy into another form of energy. ex: light from a light bulb; heat from a filament in a toaster; motor in a saw The Pathway in a Circuit Conducting wires are used to create a path in a circuit Copper is the most common conductor (wire) used Electric Circuit Diagrams and Symbols Circuit Diagram - represents an electric circuit using standard symbols Homework: Read 10.1 in your textbook and do the following questions pg. 305 - # 1 - 12 10.2 - Electric Current Electric Current (I)- flow of electric charges through a circuit Like a flowing river Measured in amperes (A) Amount of charge through a circuit at a given time. I (current in amperes); Q (charge in Coulombs); t (time in seconds) Direction of Electric Current Flows from positive to negative terminal Original thought about electricity flow Known as conventional current Flows from negative to positive terminal Modern day electricity flow (because electrons are moving) Known as electron flow Direct current (DC) Electric flow from cells (ex: watch batteries, etc.) Alternating current (AC) Electron flow reverses/alternates (electricity in your home) Series and Parallel Circuits Series circuits - current goes through each device in sequence Parallel circuits - current is split up and some of it goes through each device Measuring Electric Current Ammeter measures electric current current at a given point in the circuit Measured in amperes (A) and milliamperes (mA) Homework: Read 10.2 in your textbook and do the following questions pg. 309 - # 1 - 15 10.3 - Electrical Potential Difference (Voltage) Voltage (V)- the change in electric potential energy per coulomb of charge Measured in volts (V) Symbol: Measuring Voltage Measured using VOLTMETER Connect voltmeter in PARALLEL to a battery/cell, load, resistor, etc. Cells in Series The voltage of cells/batteries in series ADD ex: 2 - 9V batteries in series gives 18V Cells in Parallel Voltages DO NOT add up ex: 2 - 9V batteries in parallel gives 9V Homework: Read 10.3 in your textbook and do the following questions pg. 314 - # 3 - 12 10.4 - Resistors and Ohm’s Law resistor - resists/opposes the flow of electrical current Measured in ohms (Ω) Circuit Symbol: Resistor code: Ohm’s Law The ratio of the voltage across a conductor to the current through the conductor Can also be written in terms of voltage: Sample Problems Sample Problems Homework: Read 10.4 in your textbook and do the following questions pg. 319 - # 2 - 7, 10 10.5 - Resistors in Series and Parallel Circuits Sample Problems Homework: Read 10.5 in your textbook and do the following questions pg. 325 - # 2 - 8