PROPER LIGHTING IN THE HOME 



107 



with which we are not bothered indoors because the 

 rays are easily absorbed by matter such as ordinary 

 window glass. A glass has recently been made which 

 does allow ultra-violet rays to pass through it, but it 

 is more expensive than common glass. 



At the other end of the spectrum, beyond the red 

 waves, exist the longer, invisible infra-red rays. We 

 cannot conceive of their color because we cannot see 

 them. We are familiar with the infra-red rays as heat 

 rays from a fireplace or hot stove. 



Radio and wireless waves are still longer ether 

 waves. As you probably know, many of our broad- 

 casting stations broadcast on ether waves from about 

 200 to 500 meters in length. 



REFERENCES FOR FURTHER STUDY 



Texts 



Caldwell and Curtis, Science for Today, Chap. 26 



Clement, Collister and Thurston, Our Surroundings, Chap. 13 



Hunter and Whitman, My Own Science Problems, Unit 6; 



Science in Our World of Progress, Unit 6; Science in Our 



Social Life, Unit 6 

 Lake, Harley, and Welton, Exploring the World of Science, 



Chap. 21 

 Pieper and Beauchamp, Everyday Problems in Science, Unit 



15 

 Powers, Neuner, and Bruner, This Changing World, Chap. 



20 (part) 



Skilling, Tours through the World of Science, Tour 13 

 Van Buskirk and Smith, The Science of Ei>eryday Life, Chap. 



8 



Watkins and Bedell, General Science for Today, Chap. 22 

 Webb and Beauchamp, Science by Observation and Experi- 

 ment, Unit 1 (part) 

 Wood and Carpenter, Our Environment: How We Use and 



Control It, Unit 2, Topic 8 



Special references 



Black and Davis, Practical Physics 

 Godinez, The Lighting Book 

 Lynde, Physics of the Household 

 Luckiesh, Artificial Light 



WHAT YOU SHOULD AIM TO ACQUIRE FROM 

 THIS STUDY 



1. An understanding of the laws of reflection. 



2. An understanding of the principles of refraction. 



3. How light from the sun is used for illumination. 



4. A knowledge of the composition of natural light. 



5. A concept of light as a form of energy. 



TEST OF MASTERY OF THE TOPIC 



In your notebook complete the statements, answer the 

 questions, and comply with the instructions. 



1. When light strikes an opaque object it is and 



all the 



all the 



2. The angle of incidence is to the angle of 



3. Black surfaces are black because they . 

 colors. 



4. White surfaces are white because they . 

 colors. 



5. When a white light falls on a red surface it reflects 

 only the portion of the light and the other colors. 



6. is the most dependable light for judging colors. 



7. Materials that allow no light to pass through them are 

 called bodies. 



8. When light passes from a medium to one of greater 

 or lesser density the light rays are - 



9. When a ray of sunlight passes through a prism, 

 the ray is so as to give . 



10. Make a definition for light. 



11. By a drawing show an arrangement of plane mirrors 

 by means of which a soldier in a trench could see over 

 the top of the trench without exposing himself. Trace the 

 light rays from an object through the instrument to the 

 eye of an observer. Can you make such a device that will 

 work? 



12. The longest waves of the visible spectrum are 



while the shortest ones are . 



13. Infer a reason for lampshades' being made of trans- 

 lucent glass and electric light bulbs' being frosted. 



14. The rainbow is caused by slanting rays from the sun 

 shining through 



15. Ether waves that are longer than the red of the 



visible spectrum are called rays or rays. Those 



ether waves that are shorter than the violet waves of the 

 visible spectrum are called waves. 



TOPIC 3. PROPER LIGHTING IN THE HOME 



SUGGESTED PROBLEMS AND QUESTIONS 



1. What is the relation of distance to the inten- 

 sity of light? 



2. How do the walls and the ceiling of a room 

 affect light? 



3. What are the different methods of lighting? 



SUGGESTIONS AND HELPS FOR STUDY 

 1. Problem 1 can be answered very readily by doing 

 Experiment 75. 



2. In connection with problem 2, investigate in 

 your home and some public building the conditions 

 mentioned. 



3. The methods of lighting mentioned in problem 

 3 are described in the readings below and the texts 

 listed for reference. Try to find buildings in which 

 each method of lighting is used, however, in order to 

 get some first-hand information. 



4. Try to determine which form of lighting would 

 be the most economical and hygienic to use in your 

 surroundings. 



