Four Probe Method: Why 0-200mV & 0.20mA?

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Thread starter Srismiles
Start date Aug 7, 2016
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Method Probe

In summary, the voltage range for Four Probe Method is typically set between 0-200mV to ensure accurate measurement of electrical resistance without causing heating effects or signal loss. The current limit of 0.20mA prevents any temperature-related changes in resistance. The use of four probes in this method eliminates errors due to contact resistance and allows for accurate measurements of various materials. However, it may not be suitable for materials with very high or low resistivity. Special considerations must be taken when using this method for thin film measurements, and alternative methods may be more suitable in some cases.

Aug 7, 2016

Srismiles

Why we use 0 to 200 mv and 0 to 0.20 ma in four probe method and also why we use only mercury thermometer in this method?

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Aug 8, 2016

nasu

Homework Helper

These values are in no way specific to the method. And a thermometer is also not a necessary part of the method either.
You should formulate a more detailed question if you expect a relevant answer.

1. Why is the voltage range for Four Probe Method typically 0-200mV?

The voltage range for Four Probe Method is typically set between 0-200mV because this range allows for accurate measurement of the electrical resistance of a material. Higher voltages can cause heating effects and inaccuracies in the measurement, while lower voltages may not provide enough signal for accurate readings.

2. Why is the current limit set at 0.20mA for Four Probe Method?

The current limit of 0.20mA is chosen for Four Probe Method because it is a low enough value to prevent any heating effects in the material being measured. This ensures that the resistance measurement is not affected by any changes in temperature.

3. What is the significance of using four probes in this method?

The use of four probes in this method allows for accurate measurement of the electrical resistance of a material, even in the presence of contact resistance. The four probes are placed at equal distances from each other, and the two outer probes apply the current while the inner two probes measure the voltage. This eliminates any errors caused by contact resistance.

4. Is Four Probe Method suitable for all types of materials?

Four Probe Method is suitable for measuring the electrical resistance of most materials, including metals, semiconductors, and insulators. However, it may not be suitable for materials with very high or very low resistivity, as the measurement may be affected by factors such as surface roughness or changes in temperature.

5. Can Four Probe Method be used to measure the electrical resistance of thin films?

Yes, Four Probe Method can be used to measure the electrical resistance of thin films. However, special considerations must be taken into account, such as the thickness of the film and the spacing between the probes, to ensure accurate measurements. In some cases, alternative methods such as the Van der Pauw Method may be more suitable for thin film measurements.