DC Series Circuit

For this series circuit, the voltage law dictates

and the combination of resistors gives

In applying Ohm's Law with the battery voltage, you must realize that the battery voltage is applied to the total circuit (all three resistors) and not to any one of them alone. So the entire resistance must be used in Ohm's law to get the current:

For = , = , = ,

the equivalent resistance is = .

For battery voltage = V, the current is = A.

Only after the current is determined is it convenient to calculate the individual voltages for the resistors. Applying Ohm's law again for each component gives

= V, = V, = V.

The values here should confirm the voltage law, i.e., that the sum of the component voltages must equal the battery voltage.

DC circuit examples
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