【photoemission】:when the light Shoot to to a metal surface,there will be some electronics escape from the metal.【law of Ohm】:The current intensity of through a conductor is proportional to the voltage U which applied to the ends of the conductor, and is inversely proportional to the resistance of the conductor, namely I = U/R ◆要用英语表述一个理科描述时,应首先将这个描述写成简练的汉语,然后参考汉英词典及你掌握的英语语法来行文即可。