Artificial Lighting 185 



ditions being the same? 21. Why does the tungsten filament give 

 more light than the carbon filament, when the same current is used? 

 22. Compare the carbon filament and metal filament lamp as to cost 

 of current, length of service, and luminosity. 23. Describe the usual 

 plan of wiring a house for electric lighting. 24. Show by diagrams 

 how the electric meter is read and how the charge for current con- 

 sumed is calculated. 25. Mention an instance of production of light 

 without heat. Has man been able to duplicate this process? 



26. Describe the construction and operation of a hand-controlled 

 arc lamp. 27. (a) What is the highest temperature artificially pro- 

 duced? Under what conditions? (6) Compare with the supposed 

 temperature of the sun. 28. Describe the mercury vapor lamp. 

 29. What is the meaning of " electrode " ? 30. How is light produced 

 in the vapor lamp? 31. (a) What is the peculiarity of the vapor 

 light? (6) How does it affect certain colors? 32. What are the 

 important hygienic characteristics of the light? 33. Why is it espe- 

 cially useful in industrial plants and in printing and drafting rooms ? 



34. How can you show that the quality of the light affects the color 

 of an object? 35. (a) Describe a prism. (6) Of what use is it in 

 studying light and colors? 36. If the rainbow colors are brought 

 together, what color is produced? 37. What is the spectrum? 

 38. Name six colors visible in the spectrum. 39. What is the result 

 if a pure red light falls upon an object which in daylight is blue? 

 40. What three features must a lamp have in some measure in order 

 to be commercially successful? 41. (a) What is the standard usually 

 followed in providing artificial lighting? (6) Describe its essential 

 features. 42. Mention seven desirable characteristics of an artificial 

 light. 



