Read the manuel that came with your meter.

[richard7893]

For voltmeters with a finite resistance placed in a circuit, What can be done to get a correect reading of potential difference? my teacher said you would have to place a resistor between the leads of the voltmeter to get a close to correct reading, but I am just not quite wrapping my head around this idea.

 

[Delphi51]

It doesn't make sense to put a resistor across the meter (unless you mean a resistor already in the circuit).

There isn't much you can do other than to learn the resistance of the meter (often stated on the face of the meter) and do some calculations to see how it is affecting the circuit.

At one time this was a serious problem because Voltmeters had something like 20K ohms resistance per volt on the range used. However, electronic Voltmeters usually have much higher resistance due to a field affect transistor on the front end. If you have a modern meter it is unlikely that its resistance is affecting a circuit significantly.

 

[nlightner]

I would like to clarify that the manual that came with your meter is the best resource for understanding how to use and interpret its readings. However, in response to your question about getting a correct reading of potential difference when using a voltmeter with finite resistance, your teacher is correct in suggesting the use of a resistor between the leads of the voltmeter.

This is because the finite resistance of the voltmeter itself can affect the overall resistance of the circuit and therefore alter the potential difference being measured. By adding a resistor in series with the voltmeter, you are essentially creating a voltage divider circuit, which allows for a more accurate reading of potential difference.

In simpler terms, the added resistor helps to balance out the resistance in the circuit and allows for a more precise measurement of potential difference. I understand that this concept may be difficult to grasp, but it is a common practice in electrical measurements and is necessary for obtaining accurate results.

I would recommend further reading and experimentation with voltage divider circuits to gain a better understanding of this concept. Additionally, consulting with your teacher or a more experienced scientist can also help clarify any confusion you may have. Remember, as a scientist, it is important to always question and seek understanding in order to make accurate and reliable measurements.