# When a short-circuit exists, how to find the current?

#### jangchen

Homework Statement
Find the Norton equivalent circuit of the circuit in Fig 4.45 at terminals a-b
Homework Equations
When a short-circuit exists, current of other resistances with parallel is 0 I am not an English speaker, I apologize that I cannot use English well.

I have a question calculating the IN. When the terminal a-b is short-circuited, is it right that the currents are zero at 2 ohm and 6 ohm resistances?(Because they are parallel with a short-circuit.)

Also, because the current is zero at 2 ohm resistance, the Vx is zero. Is it right?

• Delta2
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#### BvU

Homework Helper
I can't think of any counter-arguments, so: yes, I think so !

• jangchen

#### jangchen

I can't think of any counter-arguments, so: yes, I think so !

#### jbriggs444

Homework Helper
Also, because the current is zero at 2 ohm resistance, the Vx is zero. Is it right?
I would reason the other way around. If terminal a is shorted to terminal b then this forces the potentials at a and b to be equal. So $V_x$ is zero. It then follows that the current across the 2 ohm resistance is zero.

• jangchen

#### jangchen

I would reason the other way around. If terminal a is shorted to terminal b then this forces the potentials at a and b to be equal. So $V_x$ is zero. It then follows that the current across the 2 ohm resistance is zero.
wow I understand it thank you!!

• BvU