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2. 12/12/2015Template copyright 2005 www.brainybetty.com2 What is a Circuit??? A circuit is any path along which electrons can flow A household circuit provides 120-Volt potential difference This means – when you plug anything into a wall outlet, one prong has a potential of 120 V, and the other has the potential of 0 V. This causes electrons to flow. How does this cause a light bulb to work? (light up)

3. 12/12/2015Template copyright 2005 www.brainybetty.com3 What is a Circuit??? Electrons flow from the prong with the high potential through the copper wiring The electrons then flow through the filament of the light bulb, which causes the light bulb to light up They then continue flowing towards the prong with low potential

4. 12/12/2015Template copyright 2005 www.brainybetty.com4 Would the light bulb still light up if the filament were broken? NO!!! The electrons MUST have a complete circuit to flow through For the continuous flow of electrons, there must be a complete circuit with NO gaps

5. 12/12/2015Template copyright 2005 www.brainybetty.com5 Current – the flow of electrons Resistance – the slowing down of the flow of electrons Voltage – produces the flow of electrons. Circuit Properties Each property has different parts of a circuit, or circuit elements

6. 12/12/2015Template copyright 2005 www.brainybetty.com6 Voltage Source A voltage source is anything that provides a potential difference This is an essential component of a circuit Batteries are a very common voltage source

7. 12/12/2015Template copyright 2005 www.brainybetty.com7 Wires Wires are the conduit through which current flows Wires are generally made of a highly conductive material like copper

8. 12/12/2015Template copyright 2005 www.brainybetty.com8 Resistors Resistors are small circuit elements that resist (slow down) the flow of electrons in a circuit Resistors are made out of materials with high resistances, like ceramic They are generally color coded by value (the bands around them have a meaning)

9. 12/12/2015Template copyright 2005 www.brainybetty.com9 Other things can be placed in circuits (lamps, motors – also resistors) (meters – measure voltage, current) These elements can be placed into a circuit in two different ways. Series Parallel

10. 12/12/2015Template copyright 2005 www.brainybetty.com10 Series Circuits 4 Characteristics 1. Current has a single pathway through the circuit 2.Resistance is cumulative (the sum of all of the resistances in the path) 3.Current in the circuit is equal to the voltage from the voltage source divided by the total resistance in the circuit (Ohm’s Law) 4. Ohm’s Law applies separately to each device, so the voltage drops across each device, according to its resistance

11. 12/12/2015Template copyright 2005 www.brainybetty.com11 Series Circuits Disadvantages: If several light bulbs are connected in series, and one goes out, what happens to the circuit? This idea may be familiar to you through some Tree decorating experiences.

12. 12/12/2015Template copyright 2005 www.brainybetty.com12 Parallel Circuits Items connected in parallel, have separate branches, any one of them can allow the electrons to flow through In a parallel circuit, all of the electrons DO NOT flow through all of the circuit elements

13. 12/12/2015Template copyright 2005 www.brainybetty.com13 Parallel Circuits 1.Each device connects the same two points in a circuit, so the voltage is the same across each device 2.The total current in the circuit splits up among the different branches (think of electrons getting to chose which branch they go down), so the current is different across each branch. More current passes through the branches with lower resistance (Ohm’s Law) 3.The total current in the circuit equals the sum of the currents in it’s parallel branches 4.As the number of branches increases, the total resistance decreases.

14. 12/12/2015Template copyright 2005 www.brainybetty.com14 Circuit Diagrams They are used to avoid assembly problems and to essentially pictures of circuits. battery resistor light bulb switch M A V Motor Ammeter Voltmeter

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