Two-probe method:

(i) Error due to contact resistance of the measuring leads,

(ii) Materials having random shapes,

(iii) Soldering of the test leads on some materials would be difficult,

(iv) Heating of the leads during soldering may inject additional impurities in materials such as semiconductors and thereby affecting the intrinsic electrical resistivity largely.

In order to overcome the above problems, four-probe method is widely proposed.

This method provides the measurement of the resistivity of the specimen having the wide variety of shapes but with uniform cross-section.

The soldering contacts proposed in two-probe method are replaced by pressure contacts to eliminate the last two problems summarized above.