# KVL for a circuit

Discussion in 'General Electronics Chat' started by allaboutcircuits4rohit, Apr 16, 2009.

Apr 16, 2009
2
0
hi,

The basic laws of the electrical is KVL and KCL.

When i was applying KVL to a particular circuit i encountered a strange doubt.

Please take look at the circuit and explain how to solve the problem.

Find the value E in the circuit.?

How to fix the polarities for 1Ω and 2Ω resistance.?

Taking this tutorial as reference.I tried my best to solve the problem.

http://www.facstaff.bucknell.edu/mastascu/eLessonsHtml/Basic/Basic5Kv.html

1.Pick a starting point on the loop you want to write KVL for
I am strating from the 4v supply.

2.
Imagine walking around the loop - clockwise or counterclockwise.

3.
When you enter an element there will be a voltage defined across that element. One end will be positive and the other negative.

my query is how to find out which end is +ve and which end is -ve.??

4.
Pick the sign of the voltage definition on the end of the element that you enter.

5.
Write down the voltage across the element using the sign you got in the previous step.

hence i arrive at the equation.

+4(-1*2)+(2*2)-3+(2.5*2)-6+(1.5*2)-E=0
E=3V.
But the solution is 9V.

Please tell me where i am going wrong ?

Also please tell me if there are two or more power supplies in a closed circuit loop.Whether there will be voltage drop or increase.???

Regards,
Ram

Last edited: Apr 16, 2009
2. ### Dave Retired Moderator

Nov 17, 2003
6,960
145
The link to the circuit on picscrazy has been removed because the page contain inappropriate material - unintentional or other wise.

Please find an alternative picture hosting service. Thank you.

Dave

3. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
You could use the albums here on ACC, it will do pretty much the same thing.

Nov 17, 2003
6,960
145