Potentiometer Loading Query

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?
 

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berkeman

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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...
 

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