2i-6i1+4i2=0 3i+4i1-9i2=0 5i-3i1-5i2=0 check i1

  • Thread starter Thread starter ritzmax72
  • Start date Start date
AI Thread Summary
The discussion revolves around solving a system of equations derived from a circuit diagram using Kirchhoff's Voltage Law (KVL). The user initially sets up three equations but finds that their solutions yield zero for all currents. A key issue identified is the omission of the 2V battery in the equations, which is crucial for correctly applying KVL. The correct approach involves incorporating the supplied voltage into the equations, leading to a total current of 1.068 amps from the 2V source. The importance of proper sign convention and voltage drops in the loop is emphasized for accurate results.
ritzmax72
Messages
15
Reaction score
0
prob.jpg
In this diagram(made at last) if i assume the curren direction as shown, I get 3 equations:
2i-6i1+4i2=0
3i+4i1-9i2=0
5i-3i1-5i2=0
check i1 is i subscript 1.(i don't know how to write subscript).
if i put in matrix form( i want to solve via matrix method only).
i am getting i=0 i1=0 i2=0, used cramer,s rule.
also tried row echeleon form. but didn't get any solution.
am i right in giving curret direction? is there any wrong convection? am i forgetting any rule.
in book the author has taken x y z(x and y in leftmost two branch AND Z IN MIDDLE branch).
he gets a good matrix with 0,0,2 in right hand side after "=" sign.(i m not writing those equations)
tell me what is the wrong with me?please neede within 1 day!
 
Engineering news on Phys.org


I'm sorry but that diagram is hard to read. I can tell you though that the system of equations represent voltages in a loop that sum to zero. Your diagram shows a 2v battery and your system of equations do not show this voltage.

That maybe one of the problems...
 


That means i should write
equation=2 volts?
But kvl says "the algebric sum of the products of currents and resistances in each of the conductor in any closed path(mesh) in a network plus the algebric sum of the emfs in that path is zero"
taking this def. Along the rhombhus path. I don't get any emf. There's only one emf i.e outermost.
 


The voltages across either two of the outer series resistors equals the supply voltage.

So, you would get I1 * 1 + (I1 - I2) * 2 = 2 ...Where the final 2 is the supply voltage
 


Yes u have done right thing.
I1*1-(I1-I2)=2. I UNDERSTAND.
BUT WHEN WE USE KVL, THEN WE CHOOSE A LOOP.THEN WE TRAVEL AROUND THAT LOOP ADD THE VOLTAGE DROPS. WE TAKE PROPER SIGN CONVENTION. THAT IS IF WE TRAVEL IN DIRECTION OF ASSUMED CURRENT THEN WE TAKE VOLTAGE DROP AS NEGATIVE AND VICE VERSA. TAKING THESE THINGS AND THREE LOOPS I HAVE WRITTEN 3 EQUATIONS. EACH EQUALS TO 0. SO I DON'T GET ANY RESULT. WHAT WRONG HAVE I DONE?
 


You haven't done anything wrong, but the currents in the circuit must depend on the supplied voltage, so you have to include equations that have this voltage in them.

There are two resistors at the top and two at the bottom that are across 2 volts. So you can make equations using that information.

The total current from the 2 V supply in your circuit is 1.068 amps.
 


Fine. Thanks all.
 

Similar threads

Replies
1
Views
2K
Replies
1
Views
2K
4
Replies
175
Views
25K
Back
Top