Lecture 4 Voltage and Current Dividers

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Lecture 4Voltage and Current Dividers

• ECE 205
• Prof. Ali Keyhani

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Voltage Division

• Provides a simple way to find the voltage across
  an element in a series circuit without solving
  the circuit equations

The elements are in series so the same current
passes through each resistor
Using Ohms law the voltage across each resistor
is found
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Voltage Division

• From the equations a pattern is derived for the
  series connected resistors
• The voltage across each resistor is equal to its
  resistance divided by the equivalent series
  resistance of the connection times the voltage
  across the series circuit.

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Example 1

• a) Find the voltage across the 560 O resistor.

b) Assume Ro is not known. Find the value of Ro
so that the voltage across the Vo is 6 V
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Example 2

• What is the voltage Vo when D1 and D0 are closed?
• B) What is the voltage value is D0 is open
• and D1 is closed?

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Current Division

• Provides a simple way to find the current through
  an element in a parallel circuit without solving
  the circuit equations

The elements are in parallel so the same voltage
appears across each conductance
Using Ohms law the current through each resistor
is found
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Current Division

• From the equations a pattern is derived for the
  resistors connected in parallel
• The source current divides among the parallel
  resistors in proportion to their conductances
  divided by the equivalent conductances in
  parallel connection.

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Example 3

• Find the current ix.
• Solution The circuit is divided into two paths.
  Then the current division rule is applied to the
  equivalent circuit.