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Electric Current & Ohm’s Law. Electric current. Rate (how fast) at which charges pass a given point Measured in Amperes or amps Current (I) Electrons moving in a wire make up current and provide energy. Two kinds of current:. Alternating current (AC)
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Electric current • Rate (how fast) at which charges pass a given point • Measured in Amperes or amps • Current (I) • Electrons moving in a wire make up current and provide energy
Two kinds of current: • Alternating current (AC) • Charges continually shift from flowing in one direction to other direction • Example: in your home • Direct Current (DC) • Charges move in one direction • Example: batteries
Voltage • A measure of pressure/force applied to electrons to make them move • Measure of the strength of current • Potential difference between two points in a circuit • V (volts) • Higher voltage means greater energy • More voltage means more current
Resistance • Opposition to the flow of electric charge, property that slows the flow of electrons • Ω Greek letter Omega • Ohms • In questions letter R is used • Called “electrical friction” means the higher your resistance, the lower the charge or current
Resistance continued • It is a characteristic property of conducting materials • Depends on thickness, length, and temperature of material • Good conductors have low resistance and poor conductors have high resistance • As temperature rises, metals’ resistance decreases
Ohm’s Law V I R x • R = V/I • V = Voltage (measured in volts V) • I = Current (measured in amps A) • R = Resistance (measured in Ohms Ω) • As resistance increase, current decrease. • As resistance decreases, current increases.