Conductors and Insulators/Resistance in Conductors/Resistivity/Temperature effects

Three conditions for resistance

1. Length of the conductor. Resistance is proportional to length. 2. Area of the conductor. Resistance is inversely proportional to area. 3. The material of the the conductor

Temperature effects on resisitance

Conductors tends to increase their resistance when temperature is increased. Insulator decrease resistance when temperature increase. The change of resistance is caused by change in resistivity of the atomic structure.

Electron drift

Electron goes from negative to positive that give rise to electric current when voltage is applied.

Theory for resistance change in different temperatures

In conductor with many free electrons and increase in temperature causes collision of electrons interrupt the current or flow of electron. However, in insulators with less free electrons there is not many collisions, so the electrons are free to move.

Resistivity formula

L= lenght A= Area p= resistivity in standard dimension.

Insulators

Insulators are materials that prevent the flow of electrons thus having no electric current. This is caused by electrons that are tightly bonded to the atom.

Positive temperature coefficient/ negative temperature coefficient

Material with resistance increase with an increase in temperature have positive temperature coefficient. Material with resistance decrease with an increase in temperature have negative temperature coefficient.

Conductors

Materials that allow electric current to flow through them because the outer electrons move easily from one atom to another. The electrons become easy to move when they are repelled by negative electric charge or attracted to a positive charge from a conductor.

Alloy

Mixture of two or more metals.

Resistance

The ability to oppose the flow of electric current. The greater resistance value, less electrons are going to flow.

Resistivity

The amount of resistance present in a piece of material with length of one meter and are of one meter square. Resistivity of standard dimension is given the symbol ρ and in units ohm* meter (Ω•m).