xiv Contents 



CHAPTER PACE 



5. RADIANT HEAT AND LIGHT 122 



2 1 . How heat gets here from the sun ; why things 



glow when they become very hot . . 122 



22. Reflection . . . . . . .129 



23. The bending of light : Refraction . . 136 



24. Focus ........ 142 



25. Magnification . . . . . .150 



26. Scattering of light : Diffusion of light . .158 



27. Color 161 



6. SOUND 174 



28. What sound is . . . . . 174 



29. Echoes 183 



30. Pitch 185 



7. MAGNETISM AND ELECTRICITY . . . .190 



3 1 . Magnets ; the compass . . . .190 



32. Static electricity ig6 



8. ELECTRICITY 203 



33. Making electricity flow .... 203 



34. Conduction of electricity . . . .213 



35. Complete circuits . . . . .219 



36. Grounded circuits 225 



37. Resistance 229 



38. The electric arc 233 



39. Short circuits and fuses .... 240 



40. Electromagnets 247 



9. MINGLING OF MOLECULES 259 



41. Solutions and emulsions .... 259 



42. Crystals 265 



43. Diffusion 268- 



44. Clouds, rain, and dew : Humidity . .274 



45. Softening due to oil or water . . .290 



