2007-02-17 01:08:51 · 5 answers · asked by patel b 1 in Science & Mathematics ➔ Engineering
Electrical resistance is the opposition to current flow.It is because of the atomic structure of the substance.For high resistive materials,the No. of free electronics will be less.When that material is heated,more free electronics occur.That is why the resitance decreases when temperature increases.
There are entirely different types of materials whose resistance increases even when the temperature increases.It is becaz of their molecular structure.
There are 2 cases
(1)If the resistance increases when temp increases,it is called
positive temp coefficient of resistance
(2)If the resistance decreases when temp increases,it is called
negative temp coefficient of resistance
Most of the materials are NTC
Conductance is the property of a material to conduct electricity
Conductivity is the degree of conductance.Is represented by the Greek letter "row"
Resistance= "row" * length of conductor/area of conductor
2007-02-17 05:27:46 · answer #1 · answered by salim h 2 · 0⤊ 0⤋
Increase in temperature increases an electrical element's resistance to electricity.
It is a measure of how easily electricity flows through an electrical element. The unit of conductance is moh the unit of resistance is ohm. Electrical conductance is the reciprocal (or opposite) of electrical resistance.
Conductivity is a measure of the given material's ability to conduct an electric current.
2007-02-17 09:26:19 · answer #2 · answered by VBPunt 1 · 0⤊ 0⤋
as temperature rises so does resistance. that is how electrical fires start.
conductivity is the ability of a material to conduct electricity over a given distance. a thinner wire has less conductivity and a longer wire also has less conductivity.
it works the same way as water through a pipe. the water pressure is the force or voltage pushing the water or current. The amperage is the water itself and the pipe is the wire.
2007-02-17 09:16:17 · answer #3 · answered by David P 3 · 0⤊ 0⤋
It depends on the substance. Metals tend to have a high positive T.C.R. (temperature coefficient of resistance) which means the resistance rises with temperature. Resistors are usually made to have low TCRs of less than 100 ppm per degree C (i.e. the resistance will change by less than 100 parts per million for every 1 degree C change in temperature. High precsion resistors can have very low TCRs of less than 5 ppm per degree C.
2007-02-17 09:18:56 · answer #4 · answered by oapboba 2 · 0⤊ 0⤋
As temperature increases resistance decreases.
2007-02-17 09:15:13 · answer #5 · answered by Iknowthisone 7 · 0⤊ 1⤋