Well, I'm quite idle in Lunar New year's holidays so I decide to do some exercises on Physics, I got stuck when solving the problem, then I tried with the suggestion on my text book, but still, I don't understand the problem, please help me out! btw, sorry, something has gotten on LaTex or I'm too bad at it, so I just place the raw syntax, sorry!(adsbygoogle = window.adsbygoogle || []).push({});

Well, we have the figure:

http://img.photobucket.com/albums/v649/maxpayne_lhp2/5.jpg

And also, we have:

[tex]\emf=48V, r(Internam resistance)=0\omega[/tex]

[tex]R_1=2\onega[/tex]

[tex]R_2=8\onega\][/tex]

[tex]R_3=6\onega[/tex]

[tex]R_4=16\onega[/tex]

Well, they told me to find out the value of [tex]U_{MN}[/tex] (Well, in my native scientific system taugh in school,[tex] U_{MN} [/tex]stands for the potential diferece between M and N.

Well, obviously, I found that

[tex]U_{MN} = U_{MA}+U_{AN}[/tex]

[tex]=U_{AN}-U_{AM}[/tex]

Then, I tended to account for the Intensity of the current thru AB via the formula:

[tex]I=\frac{\emf}{R_{AB}}[/tex]

Then, I found out that I=8 (A)

But soon, I saw something wrong and looked up in the suggestion corner, they told me:

As r=0. we have

[tex]U_{MN}=\emf.[/tex] Let the current flows thru AMB and ANB from A to B, then:

[tex]U_{AN}=\frac{U_{AB}}{R_2+R_4} . R_2 = \frac{\emf}{R_2+R_4} . R_2= 16V[/tex]

Do the same thing with [tex]U_{AM}[/tex]

Though, I don't really understand what they mean, so please help me out! What did I do wrong?

Thanks for your time and help!

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Need help on Ohm's Law

**Physics Forums | Science Articles, Homework Help, Discussion**