Does resistivity depend on electron density?

The resistivity of a substance depends on two quantities: the rate at which free electrons can move through a substance, the density of free electrons in a substance.

The greater the resistivity, the larger the field needed to produce a given current density. The lower the resistivity, the larger the current density produced by a given electrical field. Good conductors have a high conductivity and low resistivity.

The resistivity of a material depends on Its nature and the temperature of the conductor, but not on its shape and size. The SI unit of electrical resistivity is the ohm-meter. Hence resistivity is dependent on the temperature.

The relationship between relative electrical conductivity and density of different processing parameters are shown in Figures 22 – 25. The result reveals that The electrical conductivity of foam increases with the increase of density.

Conductivity is the inverse (reciprocal) of resistivity. Here, it is given by: For example, rubber is a material with large ρ and small σ — because even a very large electric field in rubber makes almost no current flow through it.

Resistance is the physical property of a substance because of which it opposes the flow of current i.e. electrons. Resistivity is the physical property of a particular substance which is having particular dimensions.

The resistance of a conductor depends on The cross sectional area of the conductor, the length of the conductor, and its resistivity. It is important to note that electrical conductivity and resistivity are inversely proportional, meaning that the more conductive something is the less resistive it is.

Expert Answer:

• Resistance depends upon:
• (i) Length of the conductor.
• (iv) Temperature of conductor.
• Resistivity depends on:
• SI Units:
• Resistance: ‘Ohm’ or Ω
• Resistivity: ‘Ohm – meter’ or Ω-m.

Electrical resistivity is The reciprocal of electrical conductivity. It is the measure of the ability of a material to oppose the flow of current. Metals are good conductors of electricity. Hence, they have low resistivity.

The extremely low resistivity (high conductivity) of silver is characteristic of metals. An insulator like glass Has low conductivity and a high resistivity.

The resistivity of a material is a measure of how strongly a material opposes the flow of electrical current. The symbol for resistivity is the lowercase Greek letter rho, ρ, and resistivity is the reciprocal of electrical conductivity: ρ=1σ.

Resistivity is indirectly proportional to the temperature. In other words, as you increase the temperature of materials, their resistivities will decrease. But this is not true for every material i.e., all materials do not have the same dependence on temperature.

SI unit of resistivity is Ohm.

There are 4 different factors which affect resistance:

• The type of material of which the resistor is made.
• The length of the resistor.
• The thickness of the resistor.
• The temperature of the conductor.

EXPLANATION: The resistance of a conductor does not depend on Pressure.

There are several factors that affect the resistance of a conductor;

• Material, eg copper, has lower resistance than steel.
• Length – longer wires have greater resistance.
• Thickness – smaller diameter wires have greater resistance.
• Temperature – heating a wire increases its resistance.

Mass Does not affect resistance.

Length of wire: Resistance is directly proportional to the length of a wire. Area of a cross-section of wire: Resistance is inversely proportional to the area of cross-section the wire. The temperature of the wire: Resistance of a wire is directly proportional to the temperature of the wire.

(i) The length of the wire, resistance is directly proportional to the length of the wire. (ii) The cross-section of the wire, resistance is inversely proportional to the cross-section of the wire. (iii) The temperature of the wire, the resistance of wire is directly proportional to the temperature of the wire.

The relationship between resistance and wire length is proportional . The resistance of a thin wire is greater than the resistance of a thick wire Because a thin wire has fewer electrons to carry the current. The relationship between resistance and the area of the cross section of a wire is inversely proportional .

The resistance of a cylindrical segment of a conductor is equal to the resistivity of the material times the length divided by the area: R≡VI=ρLA.