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 3 of 5.
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.
Ayushi said:
1 decade ago
Actually your doubt is common one, which usually strikes the mind anirban but R3 is not the load resistance infact the load is on a b terminal, and the load is not shown at the terminals. So the answer given that is 70 is correct.
(1)
Anirban Sengupta said:
1 decade ago
Sorry, but I am not convinced with the explanation. Whenever we will find Rth, then we have to remove the load resistance completely and then we will find the Rth. Load resistance will not have any impact in it. Then please explain how Rth becomes 70?
Keerthana said:
1 decade ago
1. Find Open Circuit Voltage(Vth):
Req = 68+100+120 = 288v.
Ieq = V/Req = 100/288 = .34722 A.
Voc =100-(68*.344722)-(100*.34722).
We get Vth = Voc = 41.667v.
Isc = 100/(68+100)= 0.5952A.
Rth = Vth/Isc.
Rth = 41.667/.5952 = 70 ohm.
Req = 68+100+120 = 288v.
Ieq = V/Req = 100/288 = .34722 A.
Voc =100-(68*.344722)-(100*.34722).
We get Vth = Voc = 41.667v.
Isc = 100/(68+100)= 0.5952A.
Rth = Vth/Isc.
Rth = 41.667/.5952 = 70 ohm.
(1)
Prafull gadekar said:
1 decade ago
Total Resistance,
Rt=R1+R2+R3=120+68+100 = 288ohm.
I = V/R = 100/288 = 0.347A(flowing same current in all resistance).
Now, we want to find voltage across R3=120 ohm.
V = 120*0.347 = 41.67V
Now, Rth = R3//(R1+R2) = 70 ohm.
Rt=R1+R2+R3=120+68+100 = 288ohm.
I = V/R = 100/288 = 0.347A(flowing same current in all resistance).
Now, we want to find voltage across R3=120 ohm.
V = 120*0.347 = 41.67V
Now, Rth = R3//(R1+R2) = 70 ohm.
(1)
Saleem shah said:
1 decade ago
Rth = R3(R1+R2)/(R1+R2+R3).
Rth = 120(68+100)/(68+100+120).
Rth = 120*168/288.
Rth = 20160/288.
Rth = 70 ohm.
Vth = Vs*R3/(R1+R2+R3).
Vth = 100*120/68+100+120.
Vth = 12000/288.
Vth = 41.6 v.
Rth = 120(68+100)/(68+100+120).
Rth = 120*168/288.
Rth = 20160/288.
Rth = 70 ohm.
Vth = Vs*R3/(R1+R2+R3).
Vth = 100*120/68+100+120.
Vth = 12000/288.
Vth = 41.6 v.
Smritimoy said:
1 decade ago
RTH = 68 + 100 = 168 ohm.
VTH = 100 v.
VTH = 100 v.
Shivendra soni said:
1 decade ago
Rth = (R1+R2)II(R3)
= (68+100)II(120)
= 70 ohm.
Vth = I (loop current)*R3
= [Vs/(R1+R2+R3)]*R3
= (100/288)*120
= 0.347*120
= 41.67V.
= (68+100)II(120)
= 70 ohm.
Vth = I (loop current)*R3
= [Vs/(R1+R2+R3)]*R3
= (100/288)*120
= 0.347*120
= 41.67V.
Loukya said:
1 decade ago
vs=R3*V/(R1+R2+R3)
Vs=46.7
Rth=R3(R1+R2)/R1+R2+R3
Rth=70
Vs=46.7
Rth=R3(R1+R2)/R1+R2+R3
Rth=70
Kusuma said:
1 decade ago
The resistances 68 and 100 are in series ; 68+100=168.
168 ohms is in parallel with 120 ohms. So,
Ith = (168*120) / (168+120) = 70 ohms.
Vth = R3* (Vs/R1+R2+R3).
Vth = 41.67V.
168 ohms is in parallel with 120 ohms. So,
Ith = (168*120) / (168+120) = 70 ohms.
Vth = R3* (Vs/R1+R2+R3).
Vth = 41.67V.
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