Voltage divider method - Electric Circuits

Voltage divider method



In this lesson, we will learn:

  • A review on Ohm’s Law and how to manipulate the equation (V=IR) to solve for voltage, current, and resistance.
  • How to solve problems for voltage and resistance with a shortcut equivalent of Ohm’s Law; the Voltage Divider Method general formula we will be using is:
  • What is the relationship between voltage, current, and resistance?
    • Vx=VtotalRxRtotal V_{x} = V_{total} \, \cdot \, \frac{R_{x}} {R_{total}}
  • When and how to use the Voltage Divider Method to skip to solving questions for voltage and/or resistance without having to first solve for current.
  • How we can use the Voltage Divider Method to supplement Ohm’s Law to help us in this chapter


  • The Voltage Divider Method is a formula we can utilize as a shortcut to Ohm’s Law (V=IR)(V=IR) in certain cases—when the electric circuit question is asking for voltage and/or resistance, it is no longer necessary to solve for the electric current before calculating the voltage across center resistors.

  • The general formula for the Voltage Divider Method is as follows:
    • Vx=VtotalRxRtotal V_{x} = V_{total} \, \cdot \, \frac{R_{x}} {R_{total}}

  • Where:
    • VxV_{x} is the voltage drop across a particular resistor xx
    • VtotalV_{total} is the total voltage of the circuit supplied by the battery/source
    • RxR_{x} is the resistance of a particular resistor xx
    • RtotalR_{total} is the total, combined sum of resistances of the circuit

  • In some cases, we will want to apply the voltage divider to only a section of the circuit (i.e. the parallel component only)—not to the entire circuit
    • In those cases, the total voltage will reflect the voltage amount of that portion only (i.e. the equivalent parallel resistance; VparallelV_{parallel})
    • And, the total resistance will reflect the sum of resistances of that portion only (i.e. RparallelR_{parallel})
    • In other words, you would replace the variables with “total” subscripts with the portion amount only (i.e. VtotalV_{total} = VparallelV_{parallel} and RtotalR_{total} = RparallelR_{parallel})

  • If the question provides the current II as a given, it usually hints that one or more parts of the question will not require the voltage divider (since the voltage divider formula does not include current)
    • If the question asks to solve for the current, it will require Ohm’s Law (V=IRV=IR) and can be supplemented by the voltage divider method depending on the question
  • Intro Lesson
    Introduction to the Voltage Divider Method and the Voltage Divider general formula:
  • 2.
    Voltage Divider Method for Circuits with Both Series and Parallel Configurations

    Voltage Divider
  • 3.
    Voltage Divider Method for the Ultimate Circuit Question

    Voltage Divider
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Voltage divider method

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