It’s Electrifying! E-Mag

Electric Circuit A closed path through which electrons can flow. Ex: when you turn a light switch ON, you create a CLOSED circuit, when you turn it off you are opening the circuit Phet circuit http://phet.colorado.edu/simulations/sims.php?sim=circuit_construction_kit_dc_only

Types of Circuits Series: current has only one path to take Parallel: current can follow different paths throughout the circuit.

Series Circuits

Series Circuit total resistance of the circuit is equal to the sum of individual resistance of each device in the circuit Req = R1+ R2+ R3 …

Series Circuit is the same in all parts of the circuit Ieq = I1 = I2 = I3 = …

Series Circuit Voltage drop (potential difference) can be different for each device in the circuit Sum of voltage drops in the circuit is equal to total voltage supplied by the power source Veq = V1 + V2 + V3 + …

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SERIES CIRCUIT I stays the same V adds up R adds up

Parallel Circuit

Parallel Circuit Voltage (potential difference) is the same across each device in the circuit Voltage drops across each resistor in each branch equals the total voltage provided by the battery (voltage same everywhere in the circuit VT = V1 =V2 =V3 = …

Total current in a parallel circuit equals the sum of the current in all of the branches of the circuit Itotal = I1 + I2 + I3 More branches = More resistance

Resistors in Parallel 1/Req = 1/R1 + 1/R2 + 1/R3…

Resistors in Series VS in Parallel

The basics of solving circuit problems… Parallel Circuits I adds up V is constant 1 = 1 + 1 + 1 + ... Req R1 R 2 R 3 SERIES CIRCUIT I is constant V adds up R adds up

Circuit Breakers Guards against overheating. It has a piece of wire that bends at high temps, causing a switch to “flip” which “opens” the circuit

Transformers Not these: These:

Transformers Used to step up (increase) or step down (decrease) voltage through electromagnetic induction

Electromagnetic Induction The process of inducing voltage by changing the magnetic field around a conductor

Power Transmission Power can be transmitted very long distances at high voltages and low currents, it begins at 120,000 V at power plants and is stepped down until it reaches the 120 V used in your home

Power to Your Home

110 V vs. 220 V plug

Electric Meter Each month the number of kilowatt hours (kWh) is read and you are billed according to your usage

Magnetic Poles Produce magnetic forces. Every magnet has a North and South pole. Opposite poles attract each other. Like poles repel.

Magnetic Fields space around a magnet where a magnetic force is exerted acts like an electric field

Magnetic Declination

Magnetic Domains The domain is determined by the alignment of the atoms in a magnet A strong magnet has perfectly aligned atoms

The Earth’s Magnetic Field A compass points to the earth’s magnetic field, however the geographic and magnetic fields are not perfectly aligned