Ammeter in a problem, calculating currents

[Femme_physics]

Homework Statement

http://img827.imageshack.us/img827/2602/thecircuit002.jpg

This circuit is made out of 3 resistors and an ampmeter A whose internal resistance is Ra = 10 ohms

1) Calculate the flow going through the ampmeter where R1 = 20 ohms, R2 = 30 ohms, R3 = 50 ohms

2) Come back and calculate the current that goes through the ampmeter when the ampmeter is ideal. (Ra = 0)

The Attempt at a Solution

These are the only solutions I can think of to write. I don't know the actual answer, but it doesn't seem like a complicated problem. Can anyone help me see it through?

http://img857.imageshack.us/img857/5703/rrrrz.jpg

 

[zorro]

Your first answer is correct, but second one is wrong.
When the ammeter is ideal, Ra=0 but R3≠0.

 

[Femme_physics]

Hmm.
So I = 30/50
I = 0.6 [A]

Is that it?

 

[zorro]

Yes.
Try to attempt the question at least 5 times before posting on PF. It saves time

 

[Femme_physics]

A) I can attempt it all I want, but I don't have the answer until someone tells me I'm right. As far as I'm concerned, "undefined" could've potentially been the answer.

B) Thanks