Presentation on theme: "Chapter 35: Electric Circuits"— Presentation transcript:
1 Chapter 35: Electric Circuits Conceptual PhysicsBloom High School
2 35.1 A Battery & a BulbCircuit- a complete path that the electrons takeElectrons flow from the battery (dry cell) from the negative end and travel to the positive endElectrons are provided by the battery, wires, componentsWater as analogyBattery=pumpWires=pipe or hoseBulb=device that operates
3 35.2 Electric Circuits Switch- allows for a gap in a circuit Gaps cause the electrons to stop flowingTurns the flow on and offWater analogy differencesClosing a circuit = turn the flow onOpening a faucet = turning the flow onWires can’t “leak” like a pipe or hoseSeries- devices that are connected in a rowAllows for a single path for the electronsParallel- devices are connected by their own ‘branch’Allows for several paths an electron can take
4 35.3 Series Circuits Rules of Series Circuits 1. Current flows equally through each device.2. The total resistance of the circuit is equal to the sum of the individual resistances.3. The current is equal to the voltage of the source divided by the total resistance. (Ohm’s Law)4. Ohm’s Law also applies to each individual device based on its resistance.5. The total voltage of the circuit is equal to the sum of the individual voltage drops across each device.
6 The total resistance of the circuit is equal to the sum of the individual resistances. The total resistance of this circuit is 18kW.
7 The current is equal to the voltage of the source divided by the total resistance. (Ohm’s Law)
8 Ohm’s Law also applies to each individual device based on its resistance.
9 The total voltage of the circuit is equal to the sum of the individual voltage drops across each device.
10 Series Circuits Disadvantages If one device fails, the whole circuit failsOld Christmas lightsYou don’t need to use everything to use one thingMicrowave + Toaster + TV
11 Parallel Circuits Rules of Parallel Circuits 1. Each device connects the same two points of a circuit. The voltage is equal in each ‘branch.’2. The total current is divided among the branches.a. Path of least resistance is always taken.Current inversely proportional to resistanceOhm’s Law applies separately to each branch
12 Parallel Circuits Rules, part 2 3. The total current is equal to the sum of the currents.4. As the number of branches increases, the overall resistance decreases.Overall resistance is less than the resistance of any one branch.
13 Each device connects the same two points of a circuit.
14 The total current is divided among the branches.
15 The total current is equal to the sum of the currents. Physics Physlet P.30.2
16 As the number of branches increases, the overall resistance decreases.
17 35.5 Schematic DiagramsSchematic diagrams- uses symbols to represent parts of a circuit
18 35.6 Combining Resistors in a Compound Circuit Is series, the resistances are added upIn parallel, the addition is more complicated1/R=1/R1+1/R2+1/R3…Add parallel resistances firstMake the circuit appear to be seriesAdd series resistances
19 35.7 Parallel Circuits & Overloading Homes are fed with parallel circuits from utility companiesMore appliances added allows for lower resistance for the currentGreater current can occur in the wiresOverloaded- higher amount of current in wires than is safeFire may resultShort Circuit- a new, shorter path is offered and often bypasses regular resistanceFuses- rated to self-destruct (melt) at a certain current level (amperage)Circuit breakers- designed to turn off at a certain amperage
20 Circuit Breakers Increasing current boosts an electromagnets force. When the current jumps to unsafe levels, the electromagnet pulls down a metal lever.The linkage tilts the moving contact away from the stationary contact to break the circuit.
21 Fuses Internal wire designed to melt at a prescribed amperage In older homes, look like a light bulb baseMost car fuses look similar to thisOther types of fuses