Question

how we decrease the resistance in wire???

Answer 1

answer mee??

Answer 2

The resistance of a wire is \(R=\dfrac{\rho\ L}{A}\) where \(\rho\) is a constant about the wire called resistivity (depends on the material), \(L\) is the length of the wire, and \(A\) is the cross sectional area of the wire. So what would decrease to make \(R\) decrease, and what would increase to make \(R\) decrease?

Answer 3

Also, \(V=I\ R\implies R=\dfrac{V}{I}\), so you can alter those, too.

Answer 4

relationship b/w themal energy and resistance??

Answer 5

hmm...thats good but these i knw plz tell me about thermal energy and resistance

Answer 6

Thermal energy... I'd have to search on the internet. I know \(P=I^2R=\dfrac{V^2}{R}=V\ I\), and part of the power is converted to thermal energy.

Answer 7

in resistance some of energy converted into P.E and K.E

Answer 8

why this energy waste??

Answer 9

Well, I'm not fully sure. But I do know that the energy of the electrons gets converted to \(KE\), as electrons give energy to atoms and some of that energy goes to releasing other electrons and the rest of the energy will convert to another form. I would think you're losing \(PE\).

Answer 10

are you interested in superconductor?

Answer 11

They're interesting, I suppose. Why do you ask?

Answer 12

i work on it

Answer 13

i want to share my info and gain new info about it

Answer 14

I see. I really don't know too much about them, sorry!

Answer 15

i also don't know anbout it but i want to know about it u want?

Answer 16

I might do research sometime! Right now I'm working on mechanical physics problems on here.

Answer 17

ok

Answer 18

Good luck learning!

Answer 19

reduce the impedance

Answer 20

@abb0t: Not sure if that's an answer or more of a rephrasing of the question.

In DC circuits resistance is the same as impedance.

In AC circuits they are almost the same accept for impedance accounts for the inductive/capacitive reactance as well.

For this question, the simplest answer is to increase the cross-sectional area of the wire.

Answer 21

both.

Answer 22

Simply Stated: As electrons move across a wire, they constantly collide with atoms making up a wire. These collissions impede the flow of electrons and are what cause the wire to have resistance. Thus, if the diameter of the wire were larger, it would only make sense that the electrons dont colide as much, therefore creating less resistance due to a larger wire. This is all in accordance to Ohm's law.

Answer 23

And, as per the equation for resistance of a wire, there are two other things you can change.

Also, I'd like to make a correction.. It doesn't make physical sense to alter variables of Ohm's Law as I suggested. \(R\) will be constant if you don't consider the greatened resistance due to higher thermal energy (when the wire gets hot). And, since \(R\) would be about constant (ideally), changing \(V\) would just change \(I\) proportionally, so nothing interesting comes from that equation.

Answer 24

Let's take resistivity.How does it arise inside the wire?It happens because of the drift velocity which is dependent on the collisions of microscopic particles due to thermal agitation.Higher the temperature,more frequent the colisions.These collisions cause the resistance in a wire.So the most efficient way to reduce the resistance is to decrease the numbe of collisions. i.e decrease the temperature.In fact we have superconductors which are cooled to surprising levels of temperature..

Answer 25

I agree with @vjha , but you should not that this is where Ohm's Law fails to make \(R\) constant over a variety of voltages or currents. If you increase the voltage, it will drive a higher current that will make the wire hot and more resistive. If you increase the voltage more, the current won't increase proportionally because the resistance is greater and so current will not flow as easily.

Here is a good article on a good site:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/restmp.html

Here is an example of what the resistivity of a substance might be like at different temperatures:
http://images.tutorvista.com/content/current-electricity/resistivity-with-temperature.gif

And just because you mentioned superconductivity, here is an ideal graph (never happens, but it would be convenient).
http://simpliphy.files.wordpress.com/2012/05/rho-vs-t.png
http://ffden-2.phys.uaf.edu/212_fall2003.web.dir/t.j_barry/tc_graph.gif

Those are just images I found with Google Images.

Answer 26

Yeah of course Ohm's law is not valid everywhere..and there are a large no of non ohmic devices as well.

Answer 27

Agreed! I don't know if there is a material that can have a constant \(R\) in all conditions.