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Electric Circuits and terms. Electric circuits move charges around to deliver energy. Electric Circuits. Charges move when there is a difference in electric Potential. Electric Potential (think of potential energy) is called electric Voltage
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Electric Circuits and terms Electric circuits move charges around to deliver energy
Electric Circuits • Charges move when there is a difference in electric Potential. Electric Potential (think of potential energy) is called electric Voltage • Voltage is the driving energy for a circuit and it causes charges to move around. • Charges move around and deliver energy (charges are like the tennis balls, these tennis balls (charges) carry energy (volts) which can be delivered to something in the circuit (like a light bulb) • The movement or flow of charges is called electric current (coulombs/sec = amps) • Current is measured in amps, the symbol for current is I.
Electric Circuit Simple circuit
Electric Current • The amount of electric current depends on the amount of Voltage applied (think of the amount of energy available) and depends on the resistance in the circuit • For circuits we often use the analogy of flowing water. Voltage = water pressure, current = flow rate, and resistance is the size of the pipe (or friction in the pipe)
Electric circuits • Resistance is measured in Ohms. • Light bulbs, toasters, hair dryers, etc. and basically just resistors which use up energy. • Ohms law : relates how much current flows in a circuit. • Ohms law: V = I x R, Voltage = current x resistance.
Ohm’s law: V = I x R • Example: How much current (I = amps) does a lightbulb (R = 20 ohms) use when connected to 120V (typical voltage in your house)? • V = I x R , or I = V/R = 120V/20ohms = 6amps
Electric Power • Lightbulbs are rated in power units = watts. • Power = energy per time. • For electric circuits, P = V x I.
Summarize circuit terms • Voltage: This is the amount of electical energy supplied. Charges carry around energy and transfer this to things like lightbulbs. • Current: This is the flow of charges or how many charges flow per second. Measured in Coulombs/sec = Amp (symbol is I) • Resistance: A light bulb acts like a resistor which uses up energy • Ohm’s law (relates the above 3 terms: V = I R) or Voltage = Current x Resistance.
Electric Circuits • V(volts) = I(current) x R (resistance) • P (power) = V x I = V2 / R = I2 x R • P = power =energy/time = joules/sec = watts • I = current = coulombs/sec = amps • R = resistance = ohms • V = Volts (energy) = joules/coulomb