Electrical Engineering - Circuit Theorems in AC Analysis - Discussion

Discussion :: Circuit Theorems in AC Analysis - General Questions (Q.No.2)

2. 

For the given circuit, find VTH for the circuit external to RL.

[A]. 4.6951.3° V
[B]. 4.6938.7° V
[C]. 46938.7° mV
[D]. 60° V

Answer: Option B

Explanation:

No answer description available for this question.

Biswajit Patra said: (Feb 11, 2014)  
I want the process to solve this?

Nikhil Jain said: (Jun 29, 2014)  
The value of C is j12 kohm and l is j12 kohm.

First remove RL and consider vth at the place of Rl then apply nodal analysis. You'll get the answer

Chinna said: (Aug 25, 2014)  
Can you please elaborate the explanation by substituting values @Nikhil Jain.

Sky_Net said: (Dec 5, 2014)  
Can anybody tell true procedure?

Annnonymus said: (Sep 24, 2015)  
Use kcl to find current in 15 kohm resistance. Then find voltage and that will answer.

Nhuss said: (Jan 30, 2016)  
XL = 12 K OHMS.
XC = 12 K OHMS.
RL = 49 K OHMS.
R = 15 K OHMS.
VS = 6 < 0 V.

Z = SQRT ((R+RL)^2 + (XL-XC)^2).

Z = R + RL = 49 + 15 = 64 K OHMS.

I = V/Z = 6/64K = 0.09375 mA.

VTH = 0.09375 mA x 49 k OHMS = 4.59 V.

Abdi said: (Apr 21, 2016)  
If you write equation for loop 1(branch with the inductor) and loop 2(the branch with the capacitor and R after removing RL):

Loop 1: I1Xl = 6V
Loop 2: I2(15000-j12000) = 6 (since we are interested Vth across R, we can find I2, then find the voltage across R. Because Rl is in parallel with R, the voltage across R is the same as Vth)

I2 = 6V/(15000-j120000)= 3.1235*10^-4<theta = 38.66>

Vr=Vth = 15000 * 3.1235*10^-4<theta = 38.66> = 4.685<theta = 38.66>

Hope this helps!

Hasan said: (May 12, 2016)  
Eth is the voltage across R resistance.

So, Eth = 6*15/(15 - 12j) = 4.68 < 38.7.

Siddhant Mukherjee said: (Dec 12, 2016)  
The Vth across RL is equal to the voltage across the resistor R. So for determining the voltage across R we need to find out the current flowing through R. The Current across R would be equal to I (across R) = VS/(R+XC)

So the Voltage across R would be equal to IR.

Vth = I (across R) * R.
= (VS*R)/(R + XC).

Put the values of the respective parameters and the answers would be option b = 4.69<38.7° V.

Kishorvarma said: (Dec 12, 2016)  
It's very good explanation @Nhuss.

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