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Series CircuitA series circuit is one with all the loads in a row. There is only
ONE path for the electricity to flow. If this circuit was a string
of light bulbs, and one blew out, the remaining bulbs would turn
off. 

UNDERSTANDING & CALCULATING SERIES CIRCUITS BASIC RULESSelect the rule below to see an expanded explanation


"1. The same current flows through each part of a series circuit." 

In a series circuit, the amperage at any point in the circuit is the same. This will help in calculating circuit values using Ohm's Law. You will notice from the diagram that 1 amp continually flows through
the circuit. We will get to the calculations in a moment. 

"2. The total resistance of a series circuit is equal to the sum of individual resistances." 

In a series circuit you will need to calculate the total resistance
of the circuit in order to figure out the amperage. This is done
by adding up the individual values of each component in series.


Now with these two rules we can learn how to calculate the amperage
of a circuit. Lets follow our example figure:


If we had the amperage already and wanted to know the voltage, we can use Ohm's Law as well.


"Voltage Drops" Before we go any further let's define what a "voltage drop" is. A voltage drop is the amount the voltage lowers when crossing a component from the negative side to the positive side in a series circuit. If you placed a multimeter across a resistor, the voltage drop would be the amount of voltage you are reading. This is pictured with the red arrow in the diagram.


Say a battery is supplying 12 volts to a circuit of two resistors; each having a value of 5 Ohms. According to the previous rules we figure out the total resistance.:
Next we calculate the amperage in the circuit:
Now that we know the amperage for the circuit (remember the amperage does not change in a series circuit) we can calculate what the voltage drops across each resistor is using Ohm's Law (V = I x R).


"3. Voltage applied to a series circuit is equal to the sum of the individual voltage drops."This simply means that the voltage drops have to add up to the voltage coming from the battey or batteries.
In our example above, this means that


"4. The voltage drop across a resistor in a series circuit is directly proportional to the size of the resistor."This is what we described in the Voltage Drop section above. Voltage drop = Current times Resistor size. 

"5. If the circuit is broken at any point, no current will flow."The best way to illustrate this is with a string of light bulbs. If one is burnt out, the whole thing stops working. 