# Electrical Engineering - Branch, Loop and Node Analyses - Discussion

Discussion Forum : Branch, Loop and Node Analyses - General Questions (Q.No. 14)

14.

What is the voltage drop across

*R*_{3}?Discussion:

16 comments Page 1 of 2.
Geeta H said:
9 months ago

Thanks for explaining @Somesh.

Nireeksha said:
5 years ago

Here, we can use 4-va/90.

Clex said:
6 years ago

VA.4.18 is right. Further, how can be extracted 180mv?

Somesh said:
6 years ago

For first loop:

12= 68i' + 37(i' + i")

12= 105 i' + 37 i" -----------------------1

For 2nd loop:

4= 90 i" + 37(i' + i")

4= 37 i' + 127 i" ----------------------------2

Solve equations 1 and 2 we get;

i' =114mA,

i" = 2mA,

Vr3 = i" X R,

Vr3 = 2mA X 90,

Vr3 = 180mV.

12= 68i' + 37(i' + i")

12= 105 i' + 37 i" -----------------------1

For 2nd loop:

4= 90 i" + 37(i' + i")

4= 37 i' + 127 i" ----------------------------2

Solve equations 1 and 2 we get;

i' =114mA,

i" = 2mA,

Vr3 = i" X R,

Vr3 = 2mA X 90,

Vr3 = 180mV.

Bikram said:
7 years ago

I have a question. When we have to use +ve or -ve sign in KCL nodal analysis equation?

Nehal patel said:
7 years ago

r1 + r2 + r3 - (vs1 + vs2) = r3.

Paul said:
7 years ago

I'm still not the wiser. Anyone help me?

ALI said:
8 years ago

We consider the print between R1, R2 and R3 = VA.

VA-12/86+VA-0/37+VA-4/90 = 0.

(90*37)*VA-(90*37)*12+(86*90)*VA+(37*86)*VA-(37*86)*4/(37*90*86) = 0.

11966 VA-50024 = 0.

11966 VA = 50024.

VA = 4.18.

VA-12/86+VA-0/37+VA-4/90 = 0.

(90*37)*VA-(90*37)*12+(86*90)*VA+(37*86)*VA-(37*86)*4/(37*90*86) = 0.

11966 VA-50024 = 0.

11966 VA = 50024.

VA = 4.18.

Pratik soni said:
8 years ago

Please help me who to solving the type questions &describe it's steps?

Fairoz said:
8 years ago

Super position theorem is very good one to solve this type of network. Because calculation gets very simple.

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