Why Do Some Voltmeters Not Show 10V at Full Scale on a Potentiometer?

  • Thread starter Thread starter a3sportback54
  • Start date Start date
  • Tags Tags
    Potentiometer
AI Thread Summary
The discussion centers on an experiment measuring voltage across a potentiometer connected to a 10V DC supply, using five voltmeters with different internal resistances. The voltmeter with the highest internal resistance, around 10 megohms, is identified as producing a straight line on the graph, indicating accurate voltage readings. Some voltmeters did not read 10V at full rotation due to their lower input impedance, which can cause voltage drops when measuring. Additionally, the resistance between the potentiometer wiper and the clockwise contact can affect readings, as it is unlikely to be zero ohms. Understanding these factors is crucial for accurate voltage measurements in potentiometer applications.
a3sportback54
Messages
4
Reaction score
0
The attached graph shows an experiment I performed where I had a potentiometer connected to a DC 10V supply, the voltage across the pot was measured with 5 different voltmeters of varying internal resistance. I guess the one with the highest internal resistance, to the order of 10megohm, is the straight line, v2, am I right in thinking this?

Can anyone tell me why some of the voltmeters didnt read 10V at 100% rotation?
 

Attachments

  • pot loading.jpg
    pot loading.jpg
    27.3 KB · Views: 454
Engineering news on Phys.org
a3sportback54 said:
The attached graph shows an experiment I performed where I had a potentiometer connected to a DC 10V supply, the voltage across the pot was measured with 5 different voltmeters of varying internal resistance. I guess the one with the highest internal resistance, to the order of 10megohm, is the straight line, v2, am I right in thinking this?

Can anyone tell me why some of the voltmeters didnt read 10V at 100% rotation?

Did you measure the resistance between the wiper and the CW contact? If it's not zero Ohms (probably isn't), then your lower-input-impedance voltmeters may still cause a voltage drop at full CW...
 
Thread 'Weird near-field phenomenon I get in my EM simulation'

Thread 'Weird near-field phenomenon I get in my EM simulation'

I recently made a basic simulation of wire antennas and I am not sure if the near field in my simulation is modeled correctly. One of the things that worry me is the fact that sometimes I see in my simulation "movements" in the near field that seems to be faster than the speed of wave propagation I defined (the speed of light in the simulation). Specifically I see "nodes" of low amplitude in the E field that are quickly "emitted" from the antenna and then slow down as they approach the far...
View full post »

Thread 'EMF (Electromagnetic Field) & EHS (Electromagnetic Hyper Sensitivity)'

Hello dear reader, a brief introduction: Some 4 years ago someone started developing health related issues, apparently due to exposure to RF & ELF related frequencies and/or fields (Magnetic). This is currently becoming known as EHS. (Electromagnetic hypersensitivity is a claimed sensitivity to electromagnetic fields, to which adverse symptoms are attributed.) She experiences a deep burning sensation throughout her entire body, leaving her in pain and exhausted after a pulse has occurred...
View full post »

Similar threads

Help me understand how this breadboard works?
Replies
6
Views
2K
Potentiometer alternatives
Replies
14
Views
7K
Internal Resistance Affect the Balancing Length in a Potentiometer?
Replies
12
Views
919
How Do Electrical Meters Like Voltmeters, Ohmmeters, and Ammeters Work?
Replies
24
Views
3K
Voltage across components in a zero-current circuit
Replies
4
Views
2K
Where Should the Slider Be Positioned on a Loaded Potentiometer?
Replies
6
Views
4K
Voltage query -- A power supply, resistors and a voltmeter....
Replies
46
Views
5K
Calculating voltage class ab power amp
Replies
4
Views
5K
Voltage-divider and d'Arsonval voltmeter problem
Replies
8
Views
4K
How Can a DC Milliammeter Be Adapted to Measure 150V Accurately?
Replies
11
Views
3K

Hot Threads

Recent Insights

Back
Top