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The Question & Answer (Q&A) Knowledge Managenet

The Internet has many places to ask questions about anything imaginable and find past answers on almost everything.

Table of Contents

- Why does the length of wire increase resistance?
- Does current depend on length?
- Does resistance depend on density?
- How does number density affect resistance?
- How does density affect resistance?
- Why does copper have a low resistivity?
- Does copper have a low density?
- How do you find density with resistance?
- How do you find length of resistance?
- What is resistance per unit length?
- What is the resistivity of a solution?

The moving electrons can collide with the ions in the metal. This makes it more difficult for the current to flow, and causes resistance. The resistance of a long wire is greater than the resistance of a short wire because electrons collide with more ions as they pass through.

R is proportional to ‘l’ (length)of the conductor… Here I (current) is inversely proportional to the R (resistance) there for when the length increases then the flow of current decreases and vice-versa! so, current depends on the length of the conductor.

No, resistance does not depend on the density of the material. However, it depends inversely on the density of free electrons in the material.

Number density (n). Materials with a high number density of free electrons, allow current to flow relatively easily and are called conductors. Materials with a very low number density, have a very high resistance and are called insulators.

From Fig. 2, it appears that thermal resistance increases linearly with density and that an increase in thickness augments the effect, as shown by the change in slope as thickness increases.

Pure copper has less resistance than copper containing impurities. Impurity atoms are a different size to copper atoms, so they get in the way of moving electrons. Once the ions are vibrating, they hinder the flow of the electrons. This is because the electrons will be scattered off the vibrating ions.

The two blocks below are the same size, but the copper one has a greater mass than the aluminium one. That is because copper has a higher density than aluminium. For copper ρ = 8940 ( kg m-3). …

Ohms Law and Power

- To find the Voltage, ( V ) [ V = I x R ] V (volts) = I (amps) x R (Ω)
- To find the Current, ( I ) [ I = V ÷ R ] I (amps) = V (volts) ÷ R (Ω)
- To find the Resistance, ( R ) [ R = V ÷ I ] R (Ω) = V (volts) ÷ I (amps)
- To find the Power (P) [ P = V x I ] P (watts) = V (volts) x I (amps)

To calculate the resistance R of a wire, we need to know three things: its length – the longer the wire, the greater its resistance….resistivity = resistance × area / length.

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Energy efficient cables | |

5. Transformers and the grid | |

Transformers | |

The National Grid |

Resistance per unit length is “the ratio of specific resistance or resistivity to the area of cross- section of a given conducting material”. Therefore, Resistance per unit length is the ratio of specific resistance or resistivity to the area of cross-section of given conductor in Ohm per meter.

Simply resistivity or Electrical resistivity is the resistance of the flow of current from one end to the other in a material. Electrical resistivity is a simply accessible and informative quantity to describe the material. It is the reciprocal of electrical conductivity.