Solving a Multimeter Problem with 10k Internal Resistance

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In summary, the conversation discusses the use of a 20000Ω/V meter on its 1 volt scale when attached to a 1 volt source with an internal resistance of 10k. The speaker explains that the meter has an ohms per volt spec and the load it puts on the circuit is equivalent to having a resistance of 200k ohms. They also discuss the effect of high resistance on the sensitivity of the meter. The higher the resistance, the less current the meter will draw from the circuit, which is beneficial for accurate measurements.
  • #1
scientifico
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Hello, I'm trying to learn some electronics by myself but it's quite difficult, now I'm studying the multimeters and a problem says

What will a 20000Ω/V meter read on its 1 volt scale, when attached to a 1 volt source with an internal resistance of 10k?

Can you set up this problem for me because I didn't yet understood well the argument. Thank you!
 
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  • #2
Analog meters have an ohms per volt spec. This means that if the meter a 20,000 ohms per volt spec and has a 10 volt range that means that the load the probes will put on a circuit while in the 10 volt range would be 200,000 ohms. So do the math figuring a series circuit of 10K ohms with 200K ohms and a 1 volt source.
 
  • #3
It is equivalent to having the voltmeter in series with a resistance R1 of 10k and another R2 of 20k.

Use V = IR to find V2 which is the reading of the voltmeter.
 
  • #4
But doesn't an high resistance mean a lower sensibility (because it "resist" to more electrons)? Instead why it's the opposite here?
 
  • #5
scientifico said:
But doesn't an high resistance mean a lower sensibility (because it "resist" to more electrons)? Instead why it's the opposite here?

I don't understand what you just said, but here's the thing: high resistance in a meter means the meter will have less effect on the circuit that it is measuring because it will draw less current out of it. That's a good thing.
 

1. How do I know if my multimeter has a 10k internal resistance?

The best way to determine the internal resistance of your multimeter is to consult the manufacturer's specifications or user manual. It should clearly state the internal resistance of the device.

2. Why is a 10k internal resistance important when solving multimeter problems?

The internal resistance of a multimeter affects its accuracy in measuring electrical currents. A 10k internal resistance is considered standard and helps to ensure accurate readings.

3. What should I do if my multimeter is not reading the correct values?

If your multimeter is not reading the correct values, you may need to recalibrate it. This can usually be done by following the instructions in the user manual or contacting the manufacturer for assistance.

4. Can I change the internal resistance of my multimeter?

No, the internal resistance of a multimeter is a fixed value and cannot be changed. However, some multimeters have a switch or function that allows you to adjust the range of the internal resistance.

5. Are there any other factors that can affect the accuracy of my multimeter readings?

Yes, there are several factors that can affect the accuracy of multimeter readings, such as external electromagnetic interference, temperature, and the condition of the multimeter's probes. It is important to use the multimeter in a controlled environment and regularly check and replace the probes if necessary.

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