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Series Combination of Resistors
Whenever the same current physically flows through both of the elements, two elements are said to be in series. Resistors are said to be connected in series when they are daisy chained together in a single line. Because all the current flowing through the first resistor has no other way to go, it must also pass through the second resistor and the third and so on, as seen in the image below.
R_t = R_1 +R_2 + R_3
By taking the individual values of the resistors in the above sample, the total equivalent resistance required is equivalent to 9,000 Ohms. With a single equivalent resistor having a value of 9,000 Ohms, the three individual resistors can be replaced. RT will still be the sum of all the individual resistors connected together whether 4, 5 or even more resistors are all connected together. The equivalent resistance will be greater when more resistors are added to the series. Equivalent Resistance is the general term used for the total resistance and is defined as a single value of resistance that can replace any number of resistors in series without altering the values of the voltage or current in the circuit.
The voltage, current or resistance of any series connected circuit can easily be found by using Ohm’s Law. Without affecting the total resistance, current or power to each resistor, resistors of a series circuit can be interchanged. The series resistor networks can also be thought of as voltage dividers and a series resistor circuit having N-resistive components will have N-different voltages across it while maintaining a common current. For any resistor Rx in the circuit, the voltage drop across that resistor is Vx = I*Rx.
I_R_1 = I_R_2 = I_R_3 = 1 mA
V_t = V_R_1 + V_R_2 + V_R_3 + … V_n
From the example below, the equivalent resistance, series current, voltage drop and power for each resistor can be calculated. The data can be presented in a tabular form in order to make life a little easier. Using Ohm’s Law, all the data can be obtained.