| resistance | R | ohm | Ω | objects |
| conductance | G | siemens | S | |
| resistivity | ρ | ohm meter | Ωm | materials |
| conductivity | σ | siemens every meter | S/m |
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resistors
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| none | ±20% | ||||
| pink | 10−3 | ||||
| silver | 10−2 | ±10% | |||
| gold | 10−1 | ±5% | |||
| black | 0 | 100+ | ±250 | ||
| brown | 1 | 101+ | ±1% | ±100 | |
| red | 2 | 102+ | ±2% | ±50 | |
| orange | 3 | 103+ | ±0.05% | ±15 | |
| yellow | 4 | 104+ | ±0.02% | ±25 | |
| green | 5 | 105+ | ±0.50% | ±20 | |
| blue | 6 | 106+ | ±0.25% | ±10 | |
| violet | 7 | ±0.10% | ±5 | ||
| gray | 8 | ±0.01% | ±1 | ||
| white | 9 |
materials
Resistance and resistivity. Components affecting resistance in a conducting wire.
| R= | ρℓ |
| A |
Conductors vs. Insulators
Best electric conductors: silver, copper, gold, aluminum, calcium, beryllium, tungsten
Resistivity and conductivity are reciprocals.
Conductivity in metals is a statistical/thermodynamic quantity.
Resistivity is identified by the scattering the electrons. The much more scattering, the higher the resistance.
| σ= | ne2ℓ |
| mevrms |
where…
| σ= | electrical conductivity |
| n= | density of complimentary electrons |
| e= | charge of one electron (1.60×10−19C) |
| me= | mass of an electron (9.11×10−31kg) |
| vrms= | root-mean-square rate of electrons |
| ℓ= | mean totally free path length |
Graphite
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Conducting polymers.
Resistivity of selected materials (~300K)(Note the distinction in units in between metals and nonmetals.)
| aluminum | 26.5 |
| brass | 64 |
| chromium | 126 |
| copper | 17.1 |
| gold | 22.1 |
| iron | 96.1 |
| lead | 208 |
| lithium | 92.8 |
| mercury (0°C) | 941 |
| manganese | 1440 |
| nichrome | 1500 |
| nickel | 69.3 |
| palladium | 105.4 |
| platinum | 105 |
| plutonium | 1414 |
| silver | 15.9 |
| solder | 150 |
| steel, plain | 180 |
| steel, stainless | 720 |
| tantalum | 131 |
| tin (0°C) | 115 |
| titanium (0°C) | 390 |
| tungsten | 52.8 |
| uranium (0°C) | 280 |
| zinc | 59 |
| aluminum oxide (14°C) | 1×1014 |
| aluminum oxide (300°C) | 3×1011 |
| aluminum oxide (800°C) | 4×106 |
| carbon, amorphous | 0.35 |
| carbon, diamond | 2.7 |
| carbon, graphite | 650×10−9 |
| indium believe oxide, slim film | 2000×10−9 |
| germanium | 0.46 |
| pyrex7740 | 40,000 |
| quartz | 75×1016 |
| silicon | 640 |
| silicon dioxide (20°C) | 1×1013 |
| silicon dioxide (600°C) | 70,000 |
| silicon dioxide (1300°C) | 0.004 |
| water, liquid (0°C) | 861,900 |
| water, fluid (25°C) | 181,800 |
| water, fluid (100°C) | 12,740 |
temperature
The general ascendancy is resistivity increases with raising temperature in conductors and decreases with increasing temperature in insulators. Regrettably there is no basic mathematical role to explain these relationships.
The temperature dependence of resistivity (or the reciprocal, conductivity) have the right to only be taken with quantum mechanics. In the same means that matter is one assembly of microscope particles referred to as atoms and also a beam of light is a stream of microscope particles referred to as photons, heat vibrations in a solid room a swarm of microscope particles referred to as phonons. The electrons space trying to drift towards the confident terminal of the battery, but the phonons save crashing into them. The random direction of this collisions disturbs the attempted organized motion of the electrons against the electric field. The deflection or scattering of electrons v phonons is one source of resistance. As temperature rises, the number of phonons increases and also with that the likelihood the the electrons and also phonons will certainly collide. Therefore when temperature go up, resistance goes up.
For some materials, resistivity is a linear function of temperature.
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ρ=ρ0(1+α(T−T0))
No problem is permanent.
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