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Transcript
What do you know about electricity that goes through wires? Tell me everything you can. Notes on Electric Current Flow of charge notes Imagine we have the charges below. We place a light bulb nearby. If we place an electron somewhere, can we get it to “flow” through the light bulb? Notes on Electric Current Flow of charge Imagine we have the charges below. We place a light bulb nearby. If we place an electron somewhere, can we get it to “flow” through the light bulb? Maybe, but it would be hard. There are a lot of ways our electron can go from positive to negative. Notes on Electric Current Flow of charge Imagine we have the charges below. We place a light bulb nearby. If we place an electron somewhere, can we get it to “flow” through the light bulb? Maybe, but it would be hard. There are a lot of ways our electron can go from positive to negative If we add a wire, we can force the electron to flow how we want! Notes on Electric Current Flow of charge This idea is electric current. Confusing? This of this like water. Water will flow downhill, but it can do so in may ways. If we put it in a pipe, we can direct where it flows. is a lot like Notes on Electric Current Current and amperage This flow of electrons is called electric current. We can measure how fast this flows. We call this rate amperage. 1 amp = 1 coulomb / second. The unit for current is “A”. Notes on Electric Current Current and amperage This flow of electrons is called electric current. We can measure how fast this flows. We call this rate amperage. 1 amp = 1 coulomb / second. The unit for current is “A”. In the pipe analogy, think of current as how much water flows through a section of pipe each second. High flowrate = High current! Big wire=more current Notes on Electric Current Batteries and voltage Electrons will stop flowing once they run out of electric potential, just like water stops flowing once it’s reached ground. = = Notes on Electric Current Batteries and voltage Electrons will stop flowing once they run out of electric potential, just like water stops flowing once it’s reached ground. = = The job of a battery is to pull the electrons from the positive charge and put them back on the negative charge, restoring the potential difference. Just like how a pump can bring water back up to a higher point so it can flow again. Notes on Electric Current Batteries and voltage Batteries are all about restoring electric potential. How do we measure electric potential? Notes on Electric Current Batteries and voltage Batteries are all about restoring electric potential. How do we measure electric potential? In volts! Before we said volts are how much energy each charge holds. In circuits, this represents pressure. The more voltage a battery has, the more pressure for electrons to flow. In our pipe analogy, the higher up the water gets, the more it pushes to flow down. Notes on Electric Current Resistance As electrons try to flow from high potential to low potential they may encounter things that slow them down. In the pipe analogy, this could be like a blockage in the pipe. The water still flows through, but it takes a bit of work and the pressure will go down. Notes on Electric Current Resistance As electrons try to flow from high potential to low potential they may encounter things that slow them down. In the pipe analogy, this could be like a blockage in the pipe. The water still flows through, but it takes a bit of work and the pressure will go down. In circuits, resistance is measured in ohms. The unit for resistance is Ω. Notes on Electric Current Resistance It’s important know that electricity – just like flowing water – will take the path of least resistance. Electrons flow through the wire because the wire is easier to flow through than the ground or air. Both have a very high resistance. Keep this in mind! Notes on Electric Current Electric Shock When you feel a shock, which is it that kills you: the current or the voltage? Notes on Electric Current Electric Shock When you feel a shock, which is it that kills you: the current or the voltage? Current! It’s the number of electrons, not the pressure behind them that kills. Wet skin offers less resistance than dry skin. Less resistance means more current. More current means more electrons! A current of 0.1 A can be enough to kill. equations Equations Ohm’s Law V = I•R OR V I R V: Voltage (Measured in volts) I: Current (Measured in amperes) R: Resistance (Measured in ohms) Use this equation to find voltage, current, or resistance for any circuit with 1 resistor. (to use the diagram, cover up what you want and do what’s shown to get it) vocab Vocabulary Electric Current The flow of electric charge. Amperage The volume of electrons flowing past at any one time. Voltage (circuits) The amount of energy pushing the electrons around the circuit. (Like pressure) Resistance How much the flow of electrons is slowed. Exit Question #9 What's the difference between current and voltage? a) b) c) d) e) f) current current current current current current is is is is is is like like like like like like volume, voltage is like pressure pressure, voltage is like volume speed, voltage is like pressure pressure, voltage is like speed volume, voltage is like speed speed, voltage is like volume