Why do we convert a galvanometer into voltmeter and ammeter?

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Discussion Overview

The discussion revolves around the conversion of a galvanometer into a voltmeter and ammeter, exploring the reasons and implications of this process within the context of physics education and measurement accuracy.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants inquire about the purpose of converting a galvanometer into a voltmeter and ammeter, suggesting it is to measure voltage and current.
  • Others question the necessity of this conversion when voltmeters and ammeters already exist, prompting further exploration of the educational value of the exercise.
  • One participant proposes that the conversion serves a pedagogical purpose, illustrating how electric circuits function and highlighting the limitations of measurement devices.
  • It is noted that constructing a voltmeter from a galvanometer and a resistor reveals the impact of the measuring device's internal resistance on the accuracy of measurements, particularly when the circuit's impedance approaches that of the voltmeter.
  • Participants emphasize the importance of understanding how measurement techniques can influence results, marking this as a fundamental aspect of scientific inquiry.

Areas of Agreement / Disagreement

Participants express varying views on the necessity and implications of converting a galvanometer into a voltmeter and ammeter, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

The discussion highlights limitations related to the assumptions about measurement accuracy and the dependence on circuit impedance, which are not fully resolved.

anam89
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why we convert a galvanometer into voltmeter and ammeter?
 
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anam89 said:
why we convert a galvanometer into voltmeter and ammeter?

So you can measure voltage and current.
 
TVP45 said:
So you can measure voltage and current.

it can be done by a voltmeter and ammeter...then why we need to convert a galvanometer into "voltmeter" and " ammeter".
 
anam89 said:
it can be done by a voltmeter and ammeter...then why we need to convert a galvanometer into "voltmeter" and " ammeter".

I am guessing that you encounter this in a physics class.

The reason why students are asked to do this is more pedagogical in nature, i.e. it is another illustrations of how electric circuits work. But there is also another very important aspect to this exercise. It tells you that these equipments are not "perfect" equipments. when you are measuring the potential difference, for example, you expect that your "meter" itself doesn't affect your measurement. But constructing a voltmeter using a galvanometer and another resistor shows you that there is a range of values for the impedence of the circuit in which your equipment can make an accurate-enough determination. If the impedence of the circuit you are measuring starts to approach the internal resistance of your voltmeter, then your measurement will start to go wrong very quickly.

We need to always be aware if what we measure is what we're supposed to get with minimal influence from our measuring technique. At the very least, we need to know how our measuring technique is affecting what we measure. I'd say that this is one of the first introduction to this aspect of science that a student can get.

Zz.
 

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