Solving Circuits Using Voltage & Current Dividers

This example problem uses both the voltage divider and current divider method to solve for unknown voltages, currents, and power values.

[blogan]

The analysis for i2 is confusing when explained, but you achieved the correct answer. For those who found it hard to follow, I will try to help explain below...

Since we know the current going into the node 1 is 0.5A, we can redraw the circuit using 0.5A as the current source and combine 50R + 10R (series) = 60R.

0.5A (Is = Current Source) --> 20R || 30R || 60R
i1 i2 i3

We want to find the the current across the 30R = (i2).
**** But first, let's find current across 20R or i1.

30R || 60R = 20R

NEW Circuit:
0.5A (Is) --> 20R || 20R
i1 (i2 || i3) = ix
Current Division: Is * ( ix / ( i1 + ix ) )
i1 = 0.5A ( 20R / (20R + 20R) ) = 0.25A <--- This is current across 20R or i1 (First Resistor)
* Remember, the opposite resistor is applied in the numerator *

Now we can re-draw the circuit utilizing *new* Current Source starting at node 2:

0.25 (Is) --> 30R || 60R (w/ i2 across 30R and i3 across 60R)
i2 i3
Current Division: Is * ( i3 / ( i2 + i3 ) )
i2 = 0.25A (60R / (30R + 60R) = 0.1667A

i3 = 0.5A - 0.25A - 0.1667A = 0.0833
Is i1 i2 i3

Check: KCL Rule
0.5A = 0.25A + 0.1667A + 0.0833A
Is = i1 + i2 + i3

0.5A = 0.5A (GooD)

Hope this helps :-)

[teckbeast]

Life saver, found this right before my midterm. Keep doing what your doing 😊👍

[orlandobaez]

This video was extremely helpful. You should make some on nodal analysis including super nodes, super position, operational amplifiers, and pretty much on the rest of circuits. Thanks for the help.

[zems]

This is really amazing that i'm starting to love circuit until i solve problems by myself. :(

[corrievanzyl-cjzu]

If I have an 2amp 12volt supply how will this affect the amperage output if I take the voltage down to 6volt . All DC of course.

[kamalhuzaifa]

These videos are extremely helpful to stusents and to teachers also.

[alianichol]

When calculating V2 which is 0.167A * 30 ohms = 5V wouldn't this be negative since the voltage is flowing in the opposite direction to the current i2??

[anneriaspeling]

Thank you so much for this video! I was about to give up on circuit dividers altogether before finding this. You are a legend.

[Lauramussss]

Is it possible to use the parallel addition on 60 ohms and 30 ohms instead of 60 and 20 for the current divider part? Thanks

[iftekhartahir]

I don't understand. R2 = 30 but why did you make it 15?

[mypc-mygames]

man i can't thanks u enough that was really helpful thanks a lot ^^

[perspective]

I thought the formula was V1= (R2/(R1+R2))* Vs
Also, what would the formula be if you know V1, Vs and R2 and are solving for R1? And for if you know V1, Vs and R1 and are solving for R2?

[kingalvi]

sir your lecture is very good & my question is in Video you want to find v (not) but while solving you wright v1

[d_melly]

Sir, my question is, there are many resistors there. How are you going to know that, this one is R1, R2??

[lilloud]

I don’t get how you got R2. Where did the 20||20 come from?

[joelcruz]

For the resistor where you needed to find the power. After finding the voltage, and given the resistance; why didnt you use the voltage and resistance to find the current (i = V/R) then do P = IV?

[nonayabusiness]

Question: How do you get 15 ohms from 20||60? shouldn't it be a third?

Edit: I just realized u were adding the resistance in fractions. 1/20 + 1/60 = 1/15 ohms nvm!

[pramodbhattarai]

Bro, you just make it simple, Thank you so much

[kamysamaa]

Voltage divider formula is Vout =( R2 / (R1+R2))xVin ...why in your care is Vout =(R1/(R1+R2)) xVin?...this is confusing...did you made some different notations?

[aHydrasa]

When finding i2, why do you use the resistor R2 in the numerator instead of the 30 ohm resistor that we're finding the current in?