little question

Thread Starter

Musab

Joined Sep 20, 2008
25
in a simple resistors circuit, why the measured value is always slightly less than the calculated value ?
 

bertus

Joined Apr 5, 2008
22,270
Hello,

When you measure inside a circuit, it can be that other components are parallel to the resistor so the value you measure is lower.

Greetings,
Bertus
 

hgmjr

Joined Jan 28, 2005
9,027
The best way to measure the value of a resistor that is part of a circuit is to lift or otherwise disconnect the resistor at one end and then measure it.

hgmjr
 

Thread Starter

Musab

Joined Sep 20, 2008
25
but even if there are no other components. Just resistors in series or parallel, the value is still slightly less
 

hgmjr

Joined Jan 28, 2005
9,027
Often there is a sneak current path around the resistor being measured. By disconnecting one end you can insure that the only current path seen by the meter is through the resistor being measured.

hgmjr
 
Last edited:

bertus

Joined Apr 5, 2008
22,270
Hello,

Are you pressing with your fingers to hold the resistor to measure ?
This can also lead to a lower value.

Greetings,
Bertus
 

hgmjr

Joined Jan 28, 2005
9,027
The phenomenon being referred to by scubasteve_911 becomes more pronounced as the value of the resistor being measured increases.

hgmjr
 

jtolcou

Joined Nov 1, 2008
3
The resisitor should have one leg removed from the circuit and use alligatoe clips when making measurements to eliminate your body's resitance.
 
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