Finding the current

[kaspis245]

Homework Statement

There is a circuit which is shown in the picture. $R_1=10 Ω;$ $R_2=10 Ω;$ $R_3=30 Ω$.
I need to find what ampermeter is showing.

Homework Equations

U=IR

The Attempt at a Solution

I am trying to use kirchhoff rules here.

$I_1=I_2+I_3$
$I_1R_1+I_3R_3=80$
$I_2R_2=I_3R_3$

I get that $I_3=1.14A$. Is this correct?

 

[rpthomps]

Assuming C & D are open as shown, I2 should be 0.

 

[kaspis245]

But how do I know whether there is voltage between C and D? It is not stated in the problem. In fact, the next question of this problem asks to find the voltage between C & D.

 

[NascentOxygen]

There will be a voltage between C and D, even though I₂ = 0.

 

[CWatters]

I am trying to use kirchhoff rules here.
snip
I₂R₂=I₃R₃

That last line isn't correct. The voltage across R2 and R3 are not the same.

There is nothing connected to C and D so no current flows into or out of C and D. So I₂ = 0. Think what that means for I₁ and I₃.