prastha Posted November 17, 2010 Report Share Posted November 17, 2010 I have to design an experiment to investigate how the amount of current flowing across a conducting wire affects length of the wire.Can any one suggest me appropriate design of the circuit in order to record relevant data with uncertainties to test the hypothesis.And please tell me how to measure the minute change in the length of the wire accurately as well. Reply Link to post Share on other sites More sharing options...
JavierG Posted December 21, 2010 Report Share Posted December 21, 2010 how the amount of current flowing across a conducting wire affects length of the wire.I don't really understand that. I mean, independantly of the flowing... the length of the cable won't change! right? Reply Link to post Share on other sites More sharing options...
Drake Glau Posted December 22, 2010 Report Share Posted December 22, 2010 how the amount of current flowing across a conducting wire affects length of the wire.I don't really understand that. I mean, independantly of the flowing... the length of the cable won't change! right? It could, the equation for resistance is R=pL/A where L is the length and A is the area of a cross section, the p is "rho" and is a constant or something like that if I remember right. So as the resistance decreases due to temperature increases it would make since for the either the area to increase or the length to decrease.This is a really simple circuit honestly. ----||--------A----Can't make it a circle like it should be, but you get the point I hope. I have no idea how to measure the minute length of the wire though... Reply Link to post Share on other sites More sharing options...
larry Posted December 22, 2010 Report Share Posted December 22, 2010 To measure the change in length, well, firstly use a LONG wire (to make the "minute" changes bigger). I think if you set it up so the wire is like a tightrope (strung between two clamps or whatever), and hang a small weight from it, you can measure how much the weight moves down when you turn the current on, and use trig to calculate the change in length. (btw, don't forget to include a resistor in the circuit suggested by Drake) 1 Reply Link to post Share on other sites More sharing options...
Drake Glau Posted December 22, 2010 Report Share Posted December 22, 2010 To measure the change in length, well, firstly use a LONG wire (to make the "minute" changes bigger). I think if you set it up so the wire is like a tightrope (strung between two clamps or whatever), and hang a small weight from it, you can measure how much the weight moves down when you turn the current on, and use trig to calculate the change in length. (btw, don't forget to include a resistor in the circuit suggested by Drake)That's a really good idea actually, never would of thought of that. And yes, make sure you have a resistor.Have cell on a table or something, taped to it if you need to and tape the ammeter to another table and then set up like this.----||----------------------/\/\/\/\--------------------------A-----------------------------Attach the weight with some string or whatever so that it will slide to the center of the wire. Reply Link to post Share on other sites More sharing options...
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