Why does the longer the conductor resistance, the greater the resistance? And the thicker the wire,

The resistance is calculated in the formula r= *l s

is intrinsic resistivity.

The magnitude of the resistance is proportional to the length l, and the longer the length, the greater the resistance.

The magnitude of the resistance is inversely proportional to the cross-sectional area of the wire, the thicker the wire, the larger the cross-sectional area, and the smaller the resistance.

a. The length and material of the wire are uncertain, and the resistance cannot be compared only from the cross-sectional area, which is wrong;

b. The material and cross-sectional area of the conductor are uncertain, and the resistance size cannot be compared only from the length, which is wrong;

c. When the material and cross-sectional area are the same, the larger the length, the greater the resistance, the greater the resistance, and the smaller the current when the voltage is the same.

d. When the length and cross-sectional area are the same, the resistance of the copper wire must be smaller than that of the iron wire, which is wrong

Therefore, C

s is the intrinsic resistivity.

The magnitude of the resistance is proportional to the length l, and the longer the length, the larger the cross-sectional area, and the greater the resistance.

The magnitude of the resistance is inversely proportional to the cross-sectional area of the wire, and the thicker the wire, the resistance is calculated in the formula.

r=ρ*l/

For example, the wider the road, the more people walk, and the longer it is, the more difficult it becomes.

Man is the electric charge.

There is a formula for finding the resistance of a wire: r= l s l is the length of the wire and s is the cross-sectional area of the wire, which is a constant. Gu has the phenomenon you said.

Just look at what the law of resistance says.

The thickness of the wire is approximately proportional to the magnitude of the current, and the diameter is proportional to the current, not the cross-sectional area.

For example, the current carrying capacity (approximate) of copper wire is laid in the open line

1 square - 20a;

square – 25a;

square – 30a; Nothing is forgiving.

4 square - 40a;

6 square – 50a.

20: Qiaobu 25 : 30 : 40 : 50 = 1 : 2 :

1 : 4 : Pose 6 = 1 : 2 :

The two ratios are very similar. The current carrying capacity of the copper wire is not proportional to the cross-sectional area, and 10A needs to be subtracted when laying the pipe, which shows that the ampacity is directly related to the heat dissipation of the copper wire.

Formula for resistance of conductor:

r=p*l s(p—resistivity; l—resistance length; s—the cross-sectional area of the resistance perpendicular to the current).

With this formula, you are not afraid that you do not know the calculation.

Obviously, the resistance value is proportional to the length of the conductor and inversely proportional to the cross-sectional area, so the longer the wire, the greater the resistance.

Factors that affect the magnitude of resistance: material, length, cross-sectional area, temperature.

1. Materials

The electrical resistance of conductors of different materials is generally different.

2. Length

For conductors of the same material and the same thickness, the longer the length, the greater the resistance; The shorter the length, the lower the resistance.

3. Cross-sectional area

For conductors of the same material and the same length, the larger the cross-sectional area, the smaller the resistance; The smaller the cross-sectional area, the greater the resistance.

4. Temperature

All other factors being equal, in general, the resistance becomes larger when the temperature rises and decreases when the temperature decreases.

Resistor Introduction:

Resistance (usually denoted by "R") is a physical quantity that represents the magnitude of a conductor's resistance to an electric current. The greater the resistance of the conductor, the greater the resistance of the conductor to the current.

The resistance of different conductors is generally different, and resistance is a characteristic of the conductor itself. Resistance will cause a change in the flow of electrons, and the smaller the resistance, the greater the flow of electrons, and vice versa. Whereas, superconductors have no electrical resistance.

The resistance of a conductor is usually represented by the letter r, and the unit of resistance is ohm, referred to as ohm, and the symbol is . Resistance is a physical quantity that describes the electrical conductivity of a conductor and is denoted by R. The resistance is defined by the ratio of the voltage u at both ends of the conductor to the current i passing through the conductor, i.e., r=u i.

Therefore, when the voltage at both ends of the conductor is constant, the greater the resistance, the smaller the current passing through; Conversely, the smaller the resistance, the greater the flow of electrical stupidity through it.

The formula for calculating the resistance:

r＝ρl/s

Among them is resistivity, and the resistivity of each conductor is different, and the more easily it conducts electricity, the smaller the value. l is the conductor length. s is the cross-sectional area of the conductor.

Think of it like this:

A long conductor is made up of two short conductors connected in series, so the total resistance of a long conductor is equal to the sum of the resistances of the two short conductors. Hence the high resistance of long conductors.

The thick conductor can be regarded as two conductors and filial piety, so that the cross-sectional area of the conductor becomes larger and the conductor becomes thicker. Because of the parallel resistance, the total resistance is smaller than any of them, and the parallel resistance will be smaller. So the thicker the conductor, the less resistive.

Big, small. The resistance of the conductor is related to its length, material, cross-sectional area and temperature, and the resistance of the conductor is related to the length in the case of the same material and cross-sectional area, and the longer the length, the greater the resistance; In the case of the same material and length, the resistance of the conductor is related to the cross-sectional area, and the larger the cross-sectional area, the smaller the resistance.

Resistivity describes the parameters of the conductivity of a Divine Ruler conductor. For a cylindrical homogeneous conductor made of a certain material, its resistance r is proportional to the free length l and inversely proportional to the cross-sectional area s, i.e., r = l s.