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1、Radiometry（輻射量） deals with the measurement of electromagnetic（電磁） radiation（輻射）. Such radiation consists of a flow of photons（光子）. \

　　Photons behave as either particles or waves, depending on circumstance.

　　光子可以表現為粒子或波。

　　One wave-related property of photons that cannot be disregarded is the fact that each has an associated frequency

　　波有頻率、波長屬性， 能量正比於頻率。不同頻率的光子對應不同的顏色。

2、The relationships between a photon’s wavelength λ (in meters), frequency ν (in Hertz, or cycles per second) and energy Q (in joules) are：

　　where c is the speed of light (2.998×108 meters/second) and h is Planck’s constant (6.62620 × 10−34 joule-seconds).

3、In radiometry, the basic unit is energy or radiant energy Q, measured in joules (abbreviated “J”).

　　能量單位是焦耳（joule），簡寫為 J。

　　The radiant flux（輻射流）

　　輻射流等於每秒的joules。簡稱為watt（瓦）。

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