# Finding the current

1. Jun 1, 2016

### kaspis245

1. The problem statement, all variables and given/known data
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.

2. Relevant equations
U=IR

3. 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?

2. Jun 1, 2016

### rpthomps

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

3. Jun 1, 2016

### 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.

4. Jun 1, 2016

### Staff: Mentor

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

5. Jun 3, 2016

### CWatters

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.