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ROYAL SOCIETY OF CANADA 



make it very suitable for a resistance wire; but its undesirable feature 

 of producing large thermo-electric effects makes it less desirable than 

 some other alloys for use as a standard resistence.) 



Stress-strain curves were taken for different values of current up 

 to a load of 4,515 gms., which the preliminary test showed to be quite 

 safe in not producing a permanent strain in the material. Data sheet 

 B shows the results. 



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Fig. 5. 



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Fig. 3 shows the extensions caused by the heat of the current. 

 Fig. 4 shows the stress-strain lines for different currents, taking 

 account of extension caused by heat; it can be seen that they are all 

 parallel to the no current line. 



Fig. 6 is a sample of the agreement between the stress-strain line 

 for no current in the wire, and the line for the case of a current in 

 the wire, when the extension due to the heat of the current is deducted 



In this way it is proved that the stress-strain line is the same 

 when a current is in the wire as when there is no current. Hence, 

 there can be no change in the modulus. 



