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We define the resistivity ρ of a substance so that theresistanceR of an object is directly proportional to ρ. Resistivity ρ is an intrinsic property of a material, independent of its shape or size. In contrast, the resistance R is an extrinsic property that does depend on the size an shape of the resistor.
Is resistivity intrinsic or extrinsic?
One could also have written R=ρlA. From the first relation, it implies that resistivity is a geometric property of the conductor while the second relation implies that resistance is a geometric property. However, I know that resistance is a geometric property while resistivity is an intrinsic property.
Is resistance extensive property?
Resistance and heat capacity are extensive properties.
Is electrical resistance a materials property?
Resistivity and resistance must not be confused with each other. Resistivity is a material property with an intrinsic value just like thermal conductivity, while resistance is influenced by the shape, geometry, and resistivity.
What has very high resistance?
Examples: silver, copper, gold and aluminum. Insulators: Materials that present high resistance and restrict the flow of electrons. Examples: Rubber, paper, glass, wood and plastic.
What metal has the highest resistivity?
The various high resistivity materials (including alloys) are described below:
- Tungsten: (i) Hard metal.
- Carbon: (i) ρ = 1000 to 7000 μ ohm cm, α = – 0.0002 to – 0.0008.
- Nichrome or Brightray B: Composition:
- Nichrome V or Brightray C:
- Manganin:
- Constantan or Eureka:
- German Silver or Nickel Silver or Electrum:
- Nirosta:
Is resistivity directly proportional to length?
Resistivity Summary The resistance of a conductor is directly proportional to its length (L) as R ∝ L. Thus doubling its length will double its resistance, while halving its length would halve its resistance. For example, the resistivity of copper is generally given as: 1.72 x 10–8 Ωm.
How much is the resistance of an air gap?
An air gap is completely insulator i.e. very high electrical resistance ≈ 109 Ωm, since it consists of molecules of oxygen and nitrogen.
What is the resistance of gold?
Resistivity and conductivity of various materials
| Material | Resistivity, ρ, at 20 °C (Ω·m) | Temperature coefficient (K−1) |
|---|---|---|
| Silver | 1.59×10−8 | 0.00380 |
| Copper | 1.68×10−8 | 0.00404 |
| Annealed copper | 1.72×10−8 | 0.00393 |
| Gold | 2.44×10−8 | 0.00340 |
Is pressure an intensive property?
1 Answer. You are right that intensive properties are not additive like the properties which depend on the extent of the system. Pressure is indeed an intensive property because it is force divided by an extensive quantity (area).
How do I calculate resistance?
If you know the total current and the voltage across the whole circuit, you can find the total resistance using Ohm’s Law: R = V / I. For example, a parallel circuit has a voltage of 9 volts and total current of 3 amps. The total resistance RT = 9 volts / 3 amps = 3 Ω.
Is kinetic energy intensive or extensive?
According to the definitions, density, pressure and temperature are intensive porperties and volume, internal energy are extensive properties. Symbols for representing properties: Extensive properties are symbolized by upper case (capital) letter such as V (volume), KE (kinetic energy), PE (potential energy), etc.
What causes electrical resistance?
An electric current flows when electrons move through a conductor, such as a metal wire. The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance.
How does resistance vary with pressure?
Changes in resistivity versus pressure are described by a parameter called the “pressure coefficient of electrical resistance”. Most metals have a negative pressure coefficient – i.e., their electrical resistivity decreases with increasing pressure.
Which conductor has less resistivity?
Hint: Conductivity is inversely proportional to resistivity C∝1ρ. Material which has lower resistivity is a good conductor of electricity. Alloy are the mixtures of elements, therefore alloy has higher resistivity. Element silver has lowest resistivity and hence has higher conductivity.
Does Nichrome have high resistance?
Nichrome, a non-magnetic 80/20 alloy of nickel and chromium, is the most common resistance wire for heating purposes because it has a high resistivity and resistance to oxidation at high temperatures. When used as a heating element, it is usually wound into coils.
Is heat capacity an extensive property?
The heat capacity is therefore an extensive variable since a large quantity of matter will have a proportionally large heat capacity. Specific heat is therefore an intensive variable and has units of energy per mass per degree.
Is resistance dependent on voltage?
The amount of current in a circuit depends on the amount of voltage and the amount of resistance in the circuit to oppose current flow. Just like voltage, resistance is a quantity relative between two points.
Is resistivity an intrinsic property?
Resistivity ρ is an intrinsic property of a material, independent of its shape or size. In contrast, the resistance R is an extrinsic property that does depend on the size an shape of the resistor. Recall that an object whose resistance is proportional to the voltage and current is known as a resistor.
Is pH an intensive property?
As the pH is the measure of concentration of H+ ions and as concentration is an intensive property so pH is also an intensive property. It’s intensive as it is mass independent.
Which conductor has highest resistivity?
Required Properties in high Low Resistivity or High Conductivity Conducting Material
| Sl No. | Metals | Resistivity (µΩ -cm) |
|---|---|---|
| 1 | Silver | 1.58 |
| 2 | Copper | 1.68 |
| 3 | Gold | 2.21 |
| 4 | Aluminum | 2.65 |
Why is resistance an extensive property?
To the extent that it’s appropriate to treat it as a thermodynamic quantity, given that it’s generally a description of a specific, macroscopic system (and thus violates the statistical-mechanical large-numbers assumption of thermo), resistance is extensive, always.
What is the difference between resistance and conductance?
Conductance is proportional to how much flow occurs for a given pressure, and resistance is proportional to how much pressure is required to achieve a given flow. (Conductance and resistance are reciprocals.)
Is electrical resistance an intrinsic property?
The electrical resistance (R) of a circuit component as given by Ohm’s law is the ratio of voltage (V) to current (I), usually expressed as V = IR. It should not be confused with resistivity (ρ) – an intrinsic property of the material which indicates how strongly it opposes the electric current.
What factor does not affect the resistance?
The resistance does not depend on the weight of the wire. Therefore, the correct option is weight.
