英语科普注释读物 科学知识 下PDF电子书下载

CONTENTS 1

22．WHAT“WEIGHT”MEANS 1

23．BALANCING 7

24．CENTRIFUGAL FORCE 14

25．METALS 20

26．SPRINGS AND SPRINGINESS 25

27．BRIDGES AND ARCHES 31

28．ELECTRICITY 37

29．ELECTRIC CURRENT 43

30．MAGNETS—1 49

31．MAGNETS—2 56

32．LIGHT AND DARKNESS 62

33．LIGHT AND COLOUR 68

34．REFLECTION AND MIRRORS—1 73

35．REFLECTION AND MIRRORS—2 78

36．REFRACTION AND MAGNIFYING GLASSES 83

37．EYES AND EYESIGHT 90

38．OPTICAL ILLUSIONS 97

39．OPTICAL ILLUSIONS(COLOUR) 103

40．LIGHT AND HEAT WAVES 108

41．THE SHORTEST WAVES 113

42．SOUND WAVES 118

43．HOW SOUND BEHAVES 123

VOCABULARY 129