Physics Help Forum Current in the circuit

 Electricity and Magnetism Electricity and Magnetism Physics Help Forum

 May 12th 2016, 11:58 AM #1 Junior Member   Join Date: Jan 2012 Posts: 16 Current in the circuit A cell, a resistor, a key and ammeter are arranged as shown in the circuit diagrams. The current recorded in the ammeter will be (a) maximum in (i) (b) maximum in (ii) (c) maximum in (iii) (d) the same in all the cases For the above question, I thought the current (I) would be one and the same and chose the answer (d). What is wrong in my answer. Kindly enlighten me. Jeevak likes this.
 May 12th 2016, 01:48 PM #2 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,301 Your answer of (d) is correct. I thought they might trying to trick you either by (1) changing the polarity of the ammeter relative to the battery cell so it would measure negative in some cases and positive in others - but they didn't do that, or (2) having the key (otherwise known as a switch) be open in some cases and closed in others - but it's shown as closed in all 3 cases. Who told you that answer (d) is incorrect?
 May 12th 2016, 11:55 PM #3 Junior Member   Join Date: Jan 2012 Posts: 16 Thank you sir. Since it is a question with option. The book back answer is (b). But without any explanation. So I was not able to understand how it could be (b). Is my reasoning correct?
 May 13th 2016, 05:42 AM #4 Physics Team     Join Date: Jun 2010 Location: Morristown, NJ USA Posts: 2,301 Their answer is wrong. The correct answer is (d).
 Feb 19th 2017, 04:01 AM #5 Junior Member   Join Date: Feb 2017 Posts: 7 The Total Resistance T = r+R+k+A (as they are in series) Where r,k and A are resistance of cell, key, and ammeter respectively So current in above 3 cases will be I = V/T Since V and T are equal in all 3 instances Therefore current I will be also equal. Sent from my Micromax AQ4502 using Tapatalk arangu1508 likes this. Last edited by Soumyadip; Feb 19th 2017 at 04:05 AM.
 May 2nd 2017, 06:43 AM #6 Junior Member   Join Date: May 2017 Posts: 1 it is correct option.

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# resistor, key, and ammeter are arraged

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