Also at this level standing.
Low resistance measurement methods.
Low resistance measurement method basically the trick is to pass a stable known amount of current through the low value resistor and measure the voltage drop across it.
This can be done by comparing the unknown resistance with the standard resistance.
The four wire kelvin method of measurement is preferred for resistance values below 100ω and all seaward milliohmmeters and microhmmeters use this method.
Obviously the multimeter is connected permanently as shown in picture.
2 wires carry the current known as the source or current leads and pass current through the rx.
In the above picture r is the unknown resistor and v is a multimeter set to read millivolts.
Carey foster bridge method.
What is a low resistance measurement.
1 measurement of low resistance.
This is the most crude and simplest method of measuring resistance.
At this level it is important to use test equipment that will minimize errors introduced by the test lead resistance and or contact resistance between the probe and the material being tested.
Ohm meter method 2 measurement of medium resistance.
Kelvin double bridge method.
These measurements are made using 4 separate wires.
Special connecting clips called kelvin clips are made to facilitate this kind of connection across a subject resistance.
A low resistance measurement is typically a measurement below 1 000 ohm.
The dc potentiometer method of measurement of resistance is used for measuring the unknown resistance of low value.
Following are the methods employed for measuring a resistance whose value is in the range 1ω 100kω ammeter voltmeter method.
The voltage drop across the known and unknown resistance is measured and by comparison the value of known resistance is determined.
Kelvin method this method of measurement which avoids errors caused by wire resistance is called the kelvin or 4 wire method.
2 wires carry the current known as the source or current leads and pass current through the rx.
The methods are listed below.
Some basic methods are suitable for low as well as medium resistances.
