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:
42 comments Page 4 of 5.
T.Ramachandran said:
10 years 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)
Nagesh said:
9 years ago
The resistances 68 and 100 are in series ; 68 + 100 = 168.
168 ohms is in parallel with 120 ohms. So,
Rth = (168 * 120) / (168 + 120) = 70 ohms.
Vth = R3 * (Vs/R1 + R2 + R3).
Vth = 41.67V.
168 ohms is in parallel with 120 ohms. So,
Rth = (168 * 120) / (168 + 120) = 70 ohms.
Vth = R3 * (Vs/R1 + R2 + R3).
Vth = 41.67V.
(11)
RAJIV SINGH said:
9 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:
9 years ago
168 ohms and 41.67v are correct.
Balram jadhav said:
9 years ago
By using vtg division rule (Vth) = Vs * R3/(R1 + R2 + R3).
and Rth = R1 ll (R2 + R3).
and Rth = R1 ll (R2 + R3).
(7)
Padam limbu said:
9 years ago
41.66 v and 70 Ohm is correct.
EEE said:
9 years ago
@ALL.
For the kind information, R3 is opened while calculating Rth. So, actual Rth is 100+68. This is what the Venin's theorem states.
For the kind information, R3 is opened while calculating Rth. So, actual Rth is 100+68. This is what the Venin's theorem states.
Muzaffar said:
9 years ago
I = 100/288 = 0.347A.
Rth = 120/(100+68) = 70.
Vth= 0.347 * 120 = 41.6 v.
Rth = 120/(100+68) = 70.
Vth= 0.347 * 120 = 41.6 v.
(10)
Mvs said:
8 years ago
Yes, correct @Eee.
When calculating the Venin voltage is equal to open circuit voltage.
When calculating the Venin voltage is equal to open circuit voltage.
Siddhartha said:
8 years ago
What if there is no resistance between A and B terminals?
(4)
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