Electric Circuits Chapter 35

Circuit Complete path from a positive to negative terminal of a battery Electrons flow from the negative to positive end

Parts of a circuit Battery Closed switch (allows electrons to flow) Open switch (impedes flow) Wire Resistor Light Bulb

Types of circuits Depend on how more than one device receive electrical energy Series Single pathway of electron flow Parallel Branched pathway, each of which is separate path for the flow of electrons

Series Circuits Properties Only one path for electric current to flow The amount of current passing through each device is the same Current is resisted by all three devices in series, therefore, the total resistance equals the resistance of each device RT=R1 + R2 + R3

Ohm’s Law applies to the overall circuit I = V/RT Ohm’s Law applies to each individual device on the circuit Objects with greater resistance, need higher voltage (more energy) to move the same amount of current Total voltage across the circuit equals the sum of the voltages across each individual device VT = V1 + V2 + V3

Disadvantages of Series Circuits If one device fails, it causes an open circuit where no current can flow

Properties of Parallel Circuits Each device has its own path of current flow The current in one device does not pass through the others Each device connects to the same two points on a circuit, so voltage is the same across both devices Total current divides among the parallel branches Current passes more easily into devices with low resistance, so current is inversely proportional to the resistance of that branch Ohm’s law applies separately to each branch

Total current equals the sum of each parallel branches current IT=I1 + I2 + I3 As number of parallel branches increases, the overall resistance decreases Overall resistance of the circuit is less than the resistance of any one of the parallel branches 1/RT = 1/R1 + 1/R2 + 1/R3