Take a look at this simple circuit please.

[reddvoid]

Here if we convert the 12V Voltage source in series with 3K resistor to current source
we get 4mA current in parallel with 3k resistor and this 4mA will be entering node 1 right ?
so 4mA is entering node 1 and 4mA is leaving to ground at node 2

so the current Io (from node 1 to ground ) should be zero right ?
How is he getting 1mA ?

P.S.
If his answer is wrong I'm going to sue this author for wasting my time giving wrong answers :/

 

[vk6kro]

You can't say the current in the 12 V battery is 4 mA because the 3 K resistor is not the only load on the battery. I get 3.333 mA.

The 1 mA is OK.

 

[reddvoid]

Ya right
I was confused
Now I got it.
Thank you :)