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This question has been asked a few times. I do not understand the explanation. Can someone explain how low current and voltage would work in terms of a analogue voltmeter.

An analogue voltmeter is a coil with a pointer that moves as current moves in the coil. The are a series of resistors the current has go through before going through the coil. This is the basic setup of a voltmeter. The amount of current going through the coil is used to determine what the voltage is in some circuit.

How would a analogue voltmeter be able to determine low current and high voltage, or high current and low voltage when the voltmeter works on by how much current is going through the coil?

This has confused me a lot. Can someone explain the concept of low current and high voltage in terms of a analogue voltmeter.

Your help is greatly welcomed.

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  • $\begingroup$ Are you asking about a transformer (in the title) or a voltmeter (in the question body)? They're very different devices. $\endgroup$ Jan 31, 2022 at 16:00
  • $\begingroup$ Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. $\endgroup$ Jan 31, 2022 at 16:00

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The amount of current going through the coil is used to determine what the voltage is in some circuit.

Yes, but in order for the voltmeter to have minimum effect on the voltage being measured, the input impedance (the resistors you mention) of the voltmeter has to be very high compared to the impedance between the points in the circuit where the voltage is being measured.

Can someone explain the concept of low current and high voltage in terms of an analogue voltmeter.

It's not clear what you are asking. But a voltmeter is only used to measure voltage, not to determine combinations of low current and high voltage or high current and low voltage that occur in a transformer.

An analogue voltmeter is actually an ammeter in series with a very high resistance $R_{VM}$ compared to the resistance $R_L$ across which the voltage is being measured. Since $R_{VM}>>R_L$ the equivalent resistance is approximately $R_{VM}$, assuming the resistance of the ammeter is negligible. Then the voltage "reading" is then based on $IR_{VM}$ (Ohms Law) where $I$ is the current reading of the ammeter.

Hope this helps.

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  • $\begingroup$ Thanks for the reply Bob. How is current and voltage measured in a transformer experimentally? $\endgroup$
    – shodz
    Jan 31, 2022 at 19:53
  • $\begingroup$ WIth ammeters and voltmeters. How else would you measure them? $\endgroup$
    – Bob D
    Jan 31, 2022 at 20:03
  • $\begingroup$ Hello @Bob D, Thanks for the reply. My understanding is that as Voltage increases the Current increases proportionally. Without voltage there is no current. Voltage is the pressure at which electrons are pushed. An analogue voltmeter increases its reading as the voltage increases and as the voltage increases the amount of current increases. In a stepdown transformer the voltage is reduced and the current increases, but a analogue voltmeter would give the wrong reading for the voltage as the current has increased. Would this be correct? $\endgroup$
    – shodz
    Jun 5, 2022 at 15:58
  • $\begingroup$ @shodz No that is not correct. A properly selected voltmeter requires such a small amount of current compared to the current in the circuit it is measuring so as to have negligible effect on the circuit currents and voltages. See the following for a description of an analogue voltmeter using a Darsonval movement: allaboutcircuits.com/textbook/direct-current/chpt-8/… $\endgroup$
    – Bob D
    Jun 5, 2022 at 20:39

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