![]() ![]() It occurs as the electrical energy of the charge is transformed to other forms of energy (thermal, light, mechanical, etc.) within the resistors or loads. This loss in electric potential is referred to as a voltage drop. As charge moves through the external circuit, it encounters a loss of 1.5 volts of electric potential. This is to say that the electric potential at the positive terminal is 1.5 volts greater than at the negative terminal. A 1.5-volt cell will establish an electric potential difference across the external circuit of 1.5 volts. I battery = I 1 = I 2 = I 3 = ΔV battery / R eqĮlectric Potential Difference and Voltage DropsĪs discussed in Lesson 1, the electrochemical cell of a circuit supplies energy to the charge to move it through the cell and to establish an electric potential difference across the two ends of the external circuit. R), the current in the battery and thus through every resistor can be determined by finding the ratio of the battery voltage and the equivalent resistance.Using the individual resistor values and the equation above, the equivalent resistance can be calculated. These current values are easily calculated if the battery voltage is known and the individual resistance values are known. Where I 1, I 2, and I 3 are the current values at the individual resistor locations. Mathematically, one might write I battery = I 1 = I 2 = I 3 =. It is the same at the first resistor as it is at the last resistor as it is in the battery. Current - the rate at which charge flows - is everywhere the same. The charges can be thought of as marching together through the wires of an electric circuit, everywhere marching at the same rate. Charge does NOT become used up by resistors such that there is less of it at one location compared to another. Charge does NOT pile up and begin to accumulate at any given location such that the current at one location is more than at other locations. The current in a series circuit is everywhere the same. Solve the problem then click on the Submit button to check your answer. ![]() Make yourself a problem with any number of resistors and any values. Make, solve and check your own problems by using the Equivalent Resistance widget below. Where R 1, R 2, and R 3 are the resistance values of the individual resistors that are connected in series. For series circuits, the mathematical formula for computing the equivalent resistance (R eq) is R eq = R 1 + R 2 + R 3 +. The equivalent resistance of a circuit is the amount of resistance that a single resistor would need in order to equal the overall effect of the collection of resistors that are present in the circuit. This is the concept of equivalent resistance. And the presence of four 6-Ω resistors in series would be equivalent to having one 24-Ω resistor in the circuit. The presence of three 6-Ω resistors in series would be equivalent to having one 18-Ω resistor in the circuit. As far as the battery that is pumping the charge is concerned, the presence of two 6-Ω resistors in series would be equivalent to having one 12-Ω resistor in the circuit. There is a clear relationship between the resistance of the individual resistors and the overall resistance of the collection of resistors. The actual amount of current varies inversely with the amount of overall resistance. The current is no greater at one location as it is at another location. This increased resistance serves to reduce the rate at which charge flows (also known as the current).Ĭharge flows together through the external circuit at a rate that is everywhere the same. Since there is only one pathway through the circuit, every charge encounters the resistance of every device so adding more devices results in more overall resistance. In that section, it was emphasized that the act of adding more resistors to a series circuit results in the rather expected result of having more overall resistance. Each charge passing through the loop of the external circuit will pass through each resistor in consecutive fashion.Ī short comparison and contrast between series and parallel circuits was made in the previous section of Lesson 4. In a series circuit, each device is connected in a manner such that there is only one pathway by which charge can traverse the external circuit. When all the devices are connected using series connections, the circuit is referred to as a series circuit. As mentioned in the previous section of Lesson 4, two or more electrical devices in a circuit can be connected by series connections or by parallel connections. ![]()
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