Doubt in Ammeter: Shunt Resistor or Inductance?

In summary, the conversation revolved around the discovery of a thick wire wound across the positive and negative terminals of an ammeter, which was suspected to be a shunt resistor. The question of whether inductance played a role in its function was raised, but it was determined that at low frequencies, it would not make a significant difference. The comparison to RF ammeters, which operate differently, was also mentioned.
  • #1
snb
4
0
The other day I happened to open an ammeter just out of curiosity.
What I saw was that across the positive and negative terminals a wire of considerable thickness(almost equal to the thickness of wires we use for household joints) was wound..It just had 4 or 5 turns.
I guess it should be the shunt resistor (though it wasn't a "resistor" also there was no resistor in series )...but then the fact that the wire was wound brought to my mind a doubt whether inductance has any role to play in it ?
Am I right ?
 
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  • #2
Yes, it was a shunt resistor as the meter movement was probably 1000 times more sensitive than 'amps'.

No, at the low frequencies the meter was designed for, the inductance of a few turns makes no difference. RF ammeters work on entirely different principles.

go well
 

1. What is a shunt resistor in an ammeter?

A shunt resistor is a small resistance placed in parallel with the ammeter in order to divert some of the current away from the ammeter and reduce the voltage drop across it, thereby allowing for more accurate measurements.

2. How does a shunt resistor affect the readings of an ammeter?

A shunt resistor decreases the amount of current that passes through the ammeter, which can affect the accuracy of the readings. However, it also reduces the voltage drop across the ammeter, which can help prevent damage to the instrument.

3. What is the purpose of using a shunt resistor in an ammeter?

The main purpose of a shunt resistor in an ammeter is to allow for accurate measurement of high currents without damaging the instrument. It also helps to reduce the resistance of the ammeter itself, allowing for more precise readings.

4. Can inductance affect the readings of an ammeter?

Yes, inductance can affect the readings of an ammeter. When a current flows through an inductor, it creates a magnetic field which can cause a voltage drop across the inductor. This voltage drop can interfere with the readings of the ammeter.

5. How can you determine if a shunt resistor or inductance is causing doubt in an ammeter?

To determine the cause of doubt in an ammeter, you can perform a few tests. One method is to measure the current with and without the shunt resistor in place. If the readings are significantly different, the shunt resistor may be affecting the readings. Another method is to test the ammeter with a known current source and compare the readings to the expected values. If they are significantly different, inductance may be the cause of the doubt.

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