Concept Summary Batesville High School Physics

Circuit Schematics  A schematic diagram is a symbolic representation of a circuit.  A symbol represents each item in the circuit  Lines represent wires (paths for charges).

Circuit Symbols 

Three Types of Circuits  Series  Parallel  Compound

Series Circuits  Series circuits have 1 path for charges to flow.

Series Circuits  Voltage may be different across different objects in a series circuit.  Sum of the individual voltages = source voltage  Current is the same in all parts of a series circuit.  If one “goes out”, they all “go out”

Parallel Circuits  A parallel circuit has two or more paths for charges to move.

Parallel Circuits  Voltage is the same across each element in a parallel circuit.  Current may vary through different elements in a parallel circuit.  Sum of the individual currents = source current.  If one “goes out”, the other “stays lit”.

Compound Circuits  A compound circuit has both series and parallel parts.

Adding Resistance in Series  When you add resistance in series:  Total resistance increases  Current decreases

Equivalent Series Circuits  R series = R1 + R2

Adding Resistance in Parallel  When you add resistance in parallel:  Total resistance decreases  Current increases

Equivalent Parallel Circuits

Household Circuits  Household circuits are:  parallel circuits  Typically designed to carry 15 Amperes of current - maximum.

Overloading Circuits  Since adding resistance to a parallel circuit causes current to increase, adding appliances to a household circuit causes current in the house wiring to increase.  This means wires must dissipate more heat energy (P = I 2 R).

Short Circuits  A short circuit is a very low resistance path in a circuit.  A short circuit will also cause large amounts of current to flow in a circuit and overload the circuit.

Fuses & Circuit Breakers  Fuses and circuit breakers act as automatic switches in a circuit to prevent dangerous currents from flowing.

The End