SCIENCE OF HOME AND COMMUNITY 



The light in the bulb is due to the wires or filaments coiled 

 inside, which offer so much resistance to the current that 

 they become white hot and their glowing produces light. 

 In the first lamps these filaments were usually made of 

 carbon, but now other elements, such as tungsten, are being 

 used in place of carbon. (See figures n and 12.) These 

 lamps cost more than carbon filament 

 lamps, but they are more economical 

 as they use less electricity than carbon 

 in giving the same amount of light. 

 To prevent these filaments from unit- 

 ing with oxygen and " burning up," 

 the air is pumped out of the bulbs so 

 that the interior of the bulb is a partial 

 vacuum. This accounts for the loud 

 report made when one breaks. 



One pleasing method of lighting is 

 called the indirect method, in which 

 a large shade is suspended from the 

 ceiling or fastened to the walls, with 

 the lamps placed inside of it. The 

 lamps cannot be seen and so do not dazzle the eyes ; but the 

 shades permit some diffused light to pass through, and some 

 light is reflected from the ceiling. 



STRONG TIP 

 TO PREVENT 

 TIP BREAKAGE 



FIG. 12. Mazda lamp. 



HOME PROJECT 6 



Purpose. To read the electric meter and compute the cost of 

 electricity. 



Directions. I. If you use electricity in your home, read the 

 meter. Make a drawing of the circles showing the position of 

 the pointers. Record the reading. 



2. Notice how you could cut off the current if you should 

 wish to. Can you think of any circumstances under which it 

 might be desirable to do this? 



