how we can measure the electrical resistance of a graphite sample?

Answer 1

Since graphite is a good conductor of electricity, determine electrical resistance by the usual method.
Use formula:
R=P*l/A

R=Resistance
Where P= specific resistance/resistivity
l = length of the conductor
A = Area of cross-section.

Answer 2

The electrical resistance depends on the geometry and physical composition of the graphite and where you make the measurement.

The usual way to measure resistance (between two points) is to pass a known current between the points and measure the voltage produced by that current. The resistance is then R = E / I, where R is the resistance in ohms, E is the voltage measured in volts, and I is the current measured in amperes. Clearly, the resistance will depend on where you place the two points for measurement, as well as the geometry of the graphite sample.

A more meaningful measurement might be the resistivity or specific electrical resistance of the sample. To measure that, you must construct your sample with a known geometry and make the resistance measurement on opposite ends of, say, a cylindrical rod.of known length and diameter held between two highly conductive electrodes (copper will do). The resistivity, rho, measured in ohm-meters, is then equal to R A / L, where R is the measured resistance in ohms, A is the cross sectional area (of the cylinder) in square meters, and L is the length (of the cylinder) in meters.

Answer 3

It is very simple to measure the resistance of conductive material.You take a copper bowl which Resistance known by u.or You measure that Bowl Resistance by using ohm-meter/Multi meter and noted the same(A).Put the sample of the graphite in the bowl and take reading again(B).Now you subtract the reading from B-A=resistance of graphite in ohms. But it it take at constant temperature only.