Ammeter in a problem, calculating currents

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Homework Help Overview

The discussion revolves around a circuit problem involving three resistors and an ammeter with a specified internal resistance. Participants are tasked with calculating the current through the ammeter under two conditions: with a non-ideal ammeter and with an ideal ammeter.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the current through the ammeter and expresses uncertainty about their solutions. Some participants question the correctness of the calculations, particularly regarding the ideal ammeter scenario.

Discussion Status

Some guidance has been offered regarding the calculations, with one participant confirming a calculation while another suggests the need for multiple attempts before posting. There is an ongoing exploration of the implications of the ammeter's internal resistance on the results.

Contextual Notes

Participants are discussing the impact of the ammeter's internal resistance on the circuit's behavior, and there is mention of the need for clarity on the definitions and assumptions related to the ideal and non-ideal scenarios.

Femme_physics
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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
 
Last edited by a moderator:
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Your first answer is correct, but second one is wrong.
When the ammeter is ideal, Ra=0 but R3≠0.
 
Hmm.
So I = 30/50
I = 0.6 [A]

Is that it?
 
Yes.
Try to attempt the question at least 5 times before posting on PF. It saves time :smile:
 
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
 

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