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Old May 12th 2016, 12:58 PM   #1
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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.
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Old May 12th 2016, 02:48 PM   #2
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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?
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Old May 13th 2016, 12:55 AM   #3
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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?
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Old May 13th 2016, 06:42 AM   #4
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Their answer is wrong. The correct answer is (d).
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Old Feb 19th 2017, 05:01 AM   #5
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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
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Last edited by Soumyadip; Feb 19th 2017 at 05:05 AM.
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Old May 2nd 2017, 07:43 AM   #6
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it is correct option.
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