 # Resistance in Electrical Systems

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Resistance in Electrical Systems
4.3 Notes Resistance in Electrical Systems

Properties of Materials
Conductors Insulators Have a large ability to conduct electric current They contain many free electrons Metals are good conductors Temperature influences resistance of the flow What happens to the energy when resistance is present in electrical systems? Have a lower ability to conduct electric current Electrons are tightly bound Nonmetals are good insulators What are semiconductors?

Variables and Units of Electricity
Voltage (potential difference)- the ability to accelerate an electric charge between two points in an electric field. Measured in VOLTS Current- the rate of flow in a conductor. Measured in AMPERES Resistance- measure of the ability of an electrical device to oppose flow of charge through a device Measured in OHMS (Ω)

Ohm’s Law R = ρ(L/A) Measured in (Ωm)
V = IR Voltage = (current) (resistance) I = V / R Current = (voltage) / (resistance) R = V / I Resistance = (voltage) / (current) Resistivity- a property of a material that describes its ability to resist flow of electric charge Resistivity is a physical property of individual materials and is influenced by temperature. R = ρ(L/A) Measured in (Ωm)

Types of Circuits Series Parallel
A circuit with only one path for the current to flow RSERIES= R1 + R2, R3+… A circuit in which there are multiple paths for the current to flow 1/RPARALLEL = 1/R1, + 1/R2 + 1/R3+ …

Resistors R = (First digit * 10 + second digit) (multiplier)