xiv Contents 



CHAPTER PACE 



5. RADIANT HEAT AND LIGHT . . . . .122 



21. 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 



31. Magnets; the compass . . . .190 



32. Static electricity 196 



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 . v . . . . . 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 



