THE MAGNETISM OF IRON. 



89 



the total force with which one magnet acts on the other. Ans. 

 5,376 dyne-centimeters of torque tending to turn magnets as 

 shown by arrows in Fig. 53. 



64. The two magnets specified in problem 60 are hung from a 

 balance beam as indicated in Fig. 54. Assuming that the mag- 



r-x 



Fig. 53. 



Fig. 54. 



30 cm. 



S 



nets exactly balance each other before they are magnetized, find 

 the number of grams which must be added to one pan to balance 

 the magnets after they are magnetized and specify to which pan 

 it must be added. Ans. 0.715 grams must be added to the 

 left pan. 



65. Determine the intensity H of the magnetic field at a 

 point p distant 1 8 centimeters from one pole and 24 centimeters 

 from the other pole of one of the 



magnets specified in problem 60, and 

 determine the value of the angle 0, 

 as shown in Fig. 55. Ans. H= 1.24 

 gausses, 6 = 203 46'. 5. 



66. The intensity of the earth's 

 magnetic field at Washington is 0.58 

 gauss and its dip is 62. Find its 

 horizontal and vertical components. 

 V= 0.5 12 gauss. 



67. Find the direction and intensity of the resultant magnetic 

 field at a point 30 centimeters due magnetic north of an isolated 



Ans. H= 0.272 gauss, 



