• r 649 ] 



LXXIII. The Electrical Resistance of Nickel in Magnetic 

 Fields. By W. Morris Jones, B.Sc, and J. E. Malam*. 



THE influence of magnetic fields on metallic resistance has 

 been studied by numerous investigators. The two main 

 cases observed have been those in which the magnetic field 

 is respectively parallel and perpendicular to the direction of 

 the current in the metal. The longitudinal effect for nickel 

 and iron has been investigated for small magnetic fields by 

 Williams t- Barlow J, Patterson§, Owen ||, and Heaps IF 

 have used an electromagnet and obtained results for large 

 magnetizing forces. The transverse effect for different 

 metals has been carefully studied by Grunmach **. More 

 recently, Knott ft has obtained novel results for nickel by 

 combining small longitudinal and transverse fields. 



Owen, using wires about 1 mm. long, investigated the 

 longitudinal effect for nickel up to fields of 30,000 c.G.s. units. 

 He found that the change of resistance attained a maximum 

 at a field of 2800 c.G.s., decreasing to a constant minimum 

 reached in a field of about 24,000 c.G.s. 



Heaps, using a fine wire mounted in zigzag fashion on a 

 strip of mica, studied the same effect for fields up to 

 10,000 c.G.s. units. He concluded that the increase of 

 resistance approached a maximum but did not grow less after 

 reaching the maximum. The slight decrease actually obtained 

 (about ^y of the maximum increase at a field of 10,000 c.G.s.) 

 he attributed to non-uniformity of the field and to the slight 

 transverse field introduced by bending back the wire upon 

 itself. The drop obtained by Owen (in one case at a field 

 of 10,000 c.G.s. about ^ of the maximum increase) Heaps 

 attributed to the difficulty of setting such small wires 

 accurately parallel to the field. He further suggested that 

 for very short wires the polarity of the metal might have 

 some effect in disturbing the field. 



The investigations described below were undertaken with 

 the object of throwing some light on the discrepancy between 

 the results for the longitudinal effect in nickel obtained by 

 Heaps and Owen. As the experiments proceeded their scope 

 was somewhat widened, the transverse effect and the effects 

 for intermediate orientations being included. 



An important feature of the experimental arrangements 



* Communicated by Prof. E. Taylor Jones. 



f Phil. Mag. vi. p. 693 (1903) ; ix. p. 77 (1905). 



t Proc. Roy. Soc. Ixxi. p. 30 (1902). 



§ Phil. Mag. iii. p. 643 (1902). 



|| Phil. Mag. xxi. p. 122 (1911). 



H Phil. Mag. xxii. p. 900 (1911). 



** Annalen der Physik, xxii. p. 141 (1907). 



tt Proc. Roy. Soc. Edin. xxxiii. pt. 2, no. 20 (1913). 



