16 ADVANCED ELECTRICITY AND MAGNETISM. 



magnets 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 the weight must be added. Ans. 0.715 gram must 

 be added to the left pan. 



7. Determine the intensity H of the magnetic field at a point 

 p distant 18 centimeters from one pole and 24 centimeters from 

 the other pole of one of the magnets specified in problem I, and 



K 30 cm S 



determine the value of the angle 0, as shown in Fig. 7. Ans. 

 H = 1.24 gausses, 6 = 66 1^.5. 



Note. When two causes are acting together to produce a magnetic field, the 

 field which is produced by both causes together is represented by the diagonal of 

 the parallelogram whose sides represent the field intensities at the point due to the 

 respective causes separately. 



8. The horizontal component of the earth's magnetic field at 

 a given place is 0.18 gauss, and its direction is due north. It is 

 desired to produce at the given place a resultant magnetic field 

 of 0.02 gauss intensity in a due easterly direction. Find the 

 distance and direction from the place to the point at which an 

 isolated north magnet pole of 600 units strength must be placed to 

 produce the desired result. Ans. 57.6 cm., 6 20' west of north. 



9. 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. Ans. Horizontal component = 0.272 gauss; ver- 

 tical component = 0.512 gauss. 



10. Find the direction and intensity of the resultant magnetic 

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



