Electrical Engineering - Circuit Theorems and Conversions - Discussion
Discussion Forum : Circuit Theorems and Conversions - General Questions (Q.No. 1)
1.
Find the Thevenin equivalent (VTH and RTH) between terminals A and B of the circuit given below.
4.16 V, 120 
41.6 V, 120
4.16 V, 70
41.67 V, 70
Discussion:
43 comments Page 2 of 5.
T.Ramachandran said:
1 decade ago
Vth = the voltage across the 120 Ohms. this is calculated by determining the current in the loop by applying KVL.
The KVL in the loop is,
100 - 68I - 100I - 120I = 0
=> 100 = 68I + 100I + 120I
=> I = 100/288
=> I = 0.347A
and,
Vth = 120 * I
Vth = 120 * 0.347 = 41.67V
To find Rth,
68 and 100 in series and this series combination come in parallel with 120 Ohms.
So,
Rth = (168*120/168+120)
Rth = 58.33 Ohms.
The KVL in the loop is,
100 - 68I - 100I - 120I = 0
=> 100 = 68I + 100I + 120I
=> I = 100/288
=> I = 0.347A
and,
Vth = 120 * I
Vth = 120 * 0.347 = 41.67V
To find Rth,
68 and 100 in series and this series combination come in parallel with 120 Ohms.
So,
Rth = (168*120/168+120)
Rth = 58.33 Ohms.
(1)
RAJIV SINGH said:
10 years ago
Using voltage dider rule(vth) = 100 * 120/(60 + 100 + 120) = 41.66.
And rth = (100 + 68)/(100 + 68 + 120) = 70.
And rth = (100 + 68)/(100 + 68 + 120) = 70.
(1)
Sharmila said:
10 years ago
168 ohms and 41.67v are correct.
(1)
Khinya Ram Choudhary said:
1 decade ago
Let R = R1+R2;
Rth = R||R3;
According to Thevenin Theorem:
Rth = (168*120/(168+120)) = 70 Ohm.
Vth is Thevenin voltage Between A&B,
According to Voltage Divider Rule:
Vth = Vs*R3/ (R+R3).
= 41.67 V.
Rth = R||R3;
According to Thevenin Theorem:
Rth = (168*120/(168+120)) = 70 Ohm.
Vth is Thevenin voltage Between A&B,
According to Voltage Divider Rule:
Vth = Vs*R3/ (R+R3).
= 41.67 V.
Prabha said:
1 decade ago
I can't understand.
Thangam said:
1 decade ago
I need simple formula for solving these circuit analysis.
Maheshwaran said:
1 decade ago
Vth = R3*(Vs/(R1+R2+R3))= 120*(100/(68+100+120)) = 41.67 V.
Rth = R3//(R1+R2) = (120*160) / (120 + 168)= 70 ohm.
Rth = R3//(R1+R2) = (120*160) / (120 + 168)= 70 ohm.
Anshu said:
1 decade ago
When we have to find the venin voltage b/w two terminal then, firstly we have to remove the load resistance b/w these terminal. So why all are considering r3?
Naveen said:
1 decade ago
Rth = 168.
Vth = 100 V.
Vth = 100 V.
Aaron said:
1 decade ago
In what world is R3 parallel to R1 and R2? they look in series to me. It is parallel to the load yet, but not with R1 and R2. The definition of parallel connection is that it shares two or more nodes, and this simply does not. I am confused.
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