angleofemergence出射角lightbeam光束,光柱angleofincidence入射角lightray光线??angleofreflection反射角lightsource光源angleofrefraction折射角mainsfrequency市电频率apparentdepth视深medium介质binoculars双筒望远镜melt熔化boil沸腾,煮沸meltingpoint熔点boiler锅炉microwave微波boilingpoint沸点mirage海市蜃楼,蜃景Celsiustemperaturescale摄氏温标mirror镜changeofstate物态变化multipleimage复像colour颜色multiplereflection多次反射condensation凝结,凝聚mutuallyperpendicular互相垂直的condensationpoint凝点,凝结点normal法线?coolant冷却剂object物,物体coolingcurve冷却曲??objectdistance物距criticalangle临界角opticalfibre光导纤维,光纤degree度opticalillusion光幻象,视错觉degreeCelsius摄氏度opticallydensermedium光密介质deviation偏向,偏差opticallylessdensemedium光疏介质device