176 MAGNETISM AND ELECTRICITY 



b. See if the magnetism will pass through a piece of 

 paper, thin wood or thin glass, or thin sheets of metal. 



The space around a magnet, in which there is mag- 

 netism, is called a magnetic field. The magnetic field 13 

 strongest near the poles. The magnetic field may be 

 drawn in the following way: 



Experiment 74. To Draw a Magnetic Field. 

 Apparatus: Bar magnet, iron filings in salt sifter. 

 Materials: Piece of paper. 



a. Lay the magnet upon a table, cover it with the 

 piece of paper, and slowly sift the iron filings upon the 

 paper. They will take certain positions and they may be 

 aided in arranging themselves by jarring the table a little. 

 Draw with a soft pencil a large number of lines, following 

 as closely as possible the lines which the filings are 

 taking. After drawing the lines return the filings to the 

 sifter. 



b. Hide the drawing and make another drawing 

 from memory. Then compare your two drawings and 

 see what you have omitted. You should learn to draw a 

 magnetic field from memory. 



