# Thevenins Theorem

Discussion in 'Homework Help' started by purecilia, Dec 31, 2008.

1. ### purecilia Thread Starter Member

Dec 29, 2008
12
0
Hello!!!
I need someone which can help me through out this question !!
Your help is a need for me and thankyou !!Check this question...
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1)State Thevenins Voltage Theorem
2)State Thevenins Resistance Theorem
3)From the circuit find Thevenins Voltage
4)From the circuit find also Thevenins Resistance

PLEASE SOMEONE HELP ME!!!!!

thanks

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Aug 9, 2008
138
11

Dec 29, 2008
12
0
Hi !!!

thanks

4. ### vvkannan Active Member

Aug 9, 2008
138
11
Follow these steps for solving the giving circuit
1.open circuit the load resistor and calculate the voltage across the 2k(middle one) resistor ( use ohms law).This is the voltage across the open circuit and .Remember no current flows through the rightmost resistor as it ends in open circuit

2.short the source and calculate the total resistance as seen from the load.
two 2k resistors on the left are parallel and this combination is in series with the rightmost 2k.this is the thevenin equivalent resistance.
the calculated voltage in series with the resistance is the thevenin equivalent
circuit.
You can easiy solve it now.

5. ### Thevenin's Planet Active Member

Nov 14, 2008
183
1
Hi !
It seems as if Purecilia wants numbers,instead of directions.So here goes,the thevenin theorem is an ordinary and actual practice when measuring the voltage and resistance with a multimeter.As Vvkanna said remove the resistor that is called the load resistor replace the power source with a wire to close the circuit.Use a volt-meter and measure the resistance of the whole circuit,by placing the ohms meter across the open end or terminals where the resistor was removed. What you get is the Rth or Thevenin Resistance.
Thevenin Voltage is replacing the power source and measure the voltage across the open end where the resistor was removed. Use a voltmeter.The reading you get on the dial is the Vth or Thevenin Voltage Theorem.

Stand on the shoulder of great people we must know what they know to reach beyond,

6. ### mik3 Senior Member

Feb 4, 2008
4,846
63
I guess you want to find the the thevenin equivalent circuit across RL leads.
To find Vth remove RL and find the voltage across the points where RL was connected. In this case, the upper right 2K resistor is not involved in Vth (no current through it) and thus you apply the voltage divider rule for the other two resistor to find Vth. Here it is 5V because the resistors are equal.
To find Rth remove RL, replace the battery with a short and find the resistance between the points RL was connected. Here it is 3K because the two left 2K resistors will be in parallel and equal 1K and then added to the right 2K resistor (in series).