Role of a voltmeter in an initially open circuit

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In an open circuit swung through a magnetic field, the induced electromotive force (emf) can lead to varying voltage readings, potentially resulting in either spikes or a flat graph depending on the conditions. Connecting a voltmeter across the open ends of the circuit effectively closes it, allowing for current to flow, albeit minimally due to the voltmeter's high input impedance. This high impedance means the voltmeter typically does not significantly affect the circuit under normal conditions. The degree of impact from the voltmeter depends on its specifications and the characteristics of the circuit being measured. Understanding these principles is crucial for accurate voltage measurement in open circuit scenarios.
justing943
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Hi!

Could someone briefly explain the following scenario to me please :)

If an open circuit (with the 2 ends named X and Y) hung on a string is swung through an into page magnetic field, what would the emf be? How would that change if you are asked about the voltage 'measured' between X and Y?

The answers that are debatable are between a graph where there are two spikes, one positive one negative, and a completely flat voltage graph.

If an open circuit is connected to a voltmeter (one end to each open end), how would that affect the circuit?

Thanks in advance :)
JT

edit: Sorry if this is in the wrong subforum (I suspect it belongs in the HW subforum)
 
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justing943 said:
Hi!

Could someone briefly explain the following scenario to me please :)

If an open circuit (with the 2 ends named X and Y) hung on a string is swung through an into page magnetic field, what would the emf be? How would that change if you are asked about the voltage 'measured' between X and Y?

The answers that are debatable are between a graph where there are two spikes, one positive one negative, and a completely flat voltage graph.

If an open circuit is connected to a voltmeter (one end to each open end), how would that affect the circuit?

Thanks in advance :)
JT

edit: Sorry if this is in the wrong subforum (I suspect it belongs in the HW subforum)
Hooking up a volt meter will close the circuit. A volt meter is actually measuring a current through a known impedance, but the scale is tuned into read voltage. However, the current is very low due to the high input impedance of the volt meter. So under "normal" conditions the current that flows through the volt meter is therfor not taken into account. Modern volt meters is controlled by an electronic circuit that has a few million Ohms input impedance.

How much the volt meter affect the circuit will therefor depend on the voltmeter properties and the circuit that is measured.

Vidar
 
Thanks very much for the reply :). I do believe that solves my problem :D
 

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