Solving Current Divider Rule with 30V Voltage Source

  • Thread starter Thread starter amitjakob
  • Start date Start date
  • Tags Tags
    Current
AI Thread Summary
The discussion centers on solving a circuit problem involving a 30V voltage source and a 20 Ohm resistor. Amit initially miscalculated the current flowing through the resistor, assuming a total current of 2A, but the correct division of current leads to a result of 0.5A. It was clarified that the current splits equally due to equal resistance in the branches, with 1A flowing through each path. The direction of current flow is not crucial, as a negative result indicates an incorrect initial assumption about direction. Amit gained insight into considering total resistance in circuit calculations, which will aid in future problems.
amitjakob
Messages
17
Reaction score
0
Hello everyone.
im amit, newbie in this forums, hopefully I am posting my question in the correct one.
anyways, i was trying to solve this qustion from last semester considering the attached image as a circut
with voltage source of 30V

the task was to find the current over the resistor position diagonally R=20 Ohm

My assumption was with a total equivalent current of 2A is flowing over the 5 Ohm resistor , then to be divided between 10/20 Ohm resistors and then again between 10/20 ... what gives to result of 2/3A which is ... wrong.

result is 0.5A , but why ? does it matter in which direction i consider the current flow ? how can I know which is the right direction if so ?

thanks alot, exam coming by the end of the week
cya around. amit.
 

Attachments

  • circuit.png
    circuit.png
    1.5 KB · Views: 459
Engineering news on Phys.org
You are correct with that 2A flows from the source through the 5 Ohm resistor. Now look at the equivalent resistance on both branches. Both paths have a 20 Ohm resistance (20 Ohm on left and 20||20 + 10 = 20 Ohm). So the current is divided equally to 1A each. So now that 1A flows through the 10 Ohm resistor and gets to the point where the diagonal 20 Ohm connects with the vertical 20 Ohm. Both paths have equal resistance so the current evenly splits again to 0.5A each.

The direction does not matter. In general when you solve for current and get a minus sign that just means your initial guess at the direction was wrong. The current flows the opposite way instead.
 
Allllright .. i think i got it now

from what i got from your answer one should always consider the total resistance when one calculate those sorts of problem, i tried to guess it each time with a specific resistor with a specific resistance and didnt consider other resistors might be connected and influencive.

now i know

Thanks:biggrin:

Amit, Germany.
 
Hope it helps. This stuff becomes easier as you get more experience doing these types of problems.
 
Corneo said:
Hope it helps. This stuff becomes easier as you get more experience doing these types of problems.

Thanks man, hopefully i can just forget about it after this friday, if ill pass the exam i failed last semester togather with this semester's course exam (Electical Engineering 1+2)

:-p:-p :devil::biggrin::blushing::mad::eek::bugeye::cool::zzz::cry::approve:
 

Thread 'Following up on the recent thread about Earth Resistance measurements'

I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
View full post »
Thread 'Electromagnet magnetic field issue'

Thread 'Electromagnet magnetic field issue'

Hi Guys We are a bunch a mechanical engineers trying to build a simple electromagnet. Our design is based on a very similar magnet. However, our version is about 10 times less magnetic and we are wondering why. Our coil has exactly same length, same number of layers and turns. What is possibly wrong? PIN and bracket are made of iron and are in electrical contact, exactly like the reference design. Any help will be appreciated. Thanks. edit: even same wire diameter and coil was wounded by a...
View full post »
Thread 'Beauty of old electrical and measuring things, etc.'

Thread 'Beauty of old electrical and measuring things, etc.'

Even as a kid, I saw beauty in old devices. That made me want to understand how they worked. I had lots of old things that I keep and now reviving. Old things need to work to see the beauty. Here's what I've done so far. Two views of the gadgets shelves and my small work space: Here's a close up look at the meters, gauges and other measuring things: This is what I think of as surface-mount electrical components and wiring. The components are very old and shows how...
View full post »

Similar threads

Voltage source and current source
Replies
44
Views
7K
Wheatstone bridge with four active strain gauges - extension cable length compensation formula
Replies
8
Views
2K
Buck converter will power LED's but voltage divider will not....
Replies
4
Views
2K
Engineering Why is the voltage source high potential into node 1 at -12 V in this op amp problem?
Replies
15
Views
2K
KCL got declined in Norton circuit of an ideal amplifier circuit
Replies
12
Views
2K
Can I series buck converters to get higher stepdown ratio?
Replies
10
Views
2K
Alternator torque when connected to a phase-shifted AC source
Replies
3
Views
2K
Analyze this circuit with 2 sources and 4 resistors
Replies
37
Views
4K
Using Current and Voltage Dividers
Replies
3
Views
1K
Will the bleed resistors enable a shorter path to ground or not?
2
Replies
80
Views
5K

Hot Threads

Recent Insights

Back
Top