In this blog, us will testimonial the principle of resistance, resistivity and also steps to calculation the minimum cross-sectional area and diameter of any kind of desired conductor.

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What is Resistance?

The building of a device or a circuit that opposes the motion of present through it. Resistance is measure up in Ohms (Ω). The resistance of any kind of material v a uniform cross-sectional area is identified by the complying with four factors:

The kind of materialThe lengthThe cross-sectional areaThe temperature

What is Resistivity?

Resistivity is the measure of how much a offered size of particular material resists the present flow. While products resist electrical current flow, some are far better at conducting it 보다 others. Resistivity is provided to compare the inherent resistance attributes of various materials. Materials that conveniently conduct existing are described as conductors. Conductors have actually a short resistivity. While the materials that perform not easily conduct current are described as insulators. Insulators have a high resistivity. The resistivity of a material plays crucial role in choosing the materials used for electric wire.

Now the we know the ide of resistance and resistivity clearly, let’s evaluation the basic relationship of simple conductor resistance, which suggests that the resistance that a offered conductor is same to the material resistivity time the proportion of its size to the cross-sectional area. This can aid us to calculation the minimum cross-sectional area and also diameter of any desired conductor.

Let’s job-related out an example to know the measures to calculation the minimum cross-sectional area and diameter of any kind of desired conductor.

Example: What is the minimum cross-sectional area and diameter the conductor because that a 750-meter-long copper wire having a best resistance that 0.2 ohms?

Minimum Cross-sectional Area:

To fix this problem, us will use the basic relationship because that calculating conductor resistance utilizing the formula below:

Resistance = Resistivity * (Length / Area )


R =


R = Resistance that material, in Ohms

Ρ = product Resistivity, in Ohms per meter

L = Conductor Length, in meters

A = Cross-sectional Area, in square meters

In order to usage this basic relationship to solve our example problem, we call for the particular resistance or resistivity that copper. Note that we gain the resistivity that conductor materials from the table that conductor resistivity and we understand now that copper has a resistivity of 1.72 x 10e-8 ohms per meter.

While fixing Conductor Resistance, remember come express resistance in ohms, material resistivity in ohms every meter, conductor length in meters, and cross-sectional area in square meters because that this relationship to it is in valid. We have the right to then move on to calculation the cross-sectional area that the cable by substituting for the recognized quantities in the example. 

A =

Eq. (1)




Diameter the the conductor:

Area that a circle deserve to be represented using below formula. Us will need to rearrange the formula to resolve for diameter.

A =


4*A =



d =


We have the right to now substitute our obtained cross-sectional area worth from Eq. (1) into this relationship and also calculate the diameter the the copper wire to arrive at a diameter of 0.009062 meters.

See more: Lowest Common Multiple Of 2 And 3, Least Common Multiple Of 2 And 3

d = 4*0.00006453.1415920.5


d = (8.212395*10-5)0.5

d = 0.009062 m

Now the we have actually the equipment values, we will convert them and also express our final answer using the traditional units. 

A = 0.0000645 m2 = 64.5 mm2

d = 0.009062 m = 9.062 mm

Thereby, us conclude that our copper cable must have actually a minimum cross-sectional area of no much less than 64.5 mm^2 and also a diameter the no less than 9.062 mm.