题目

如图所示，用波长为的单色光照射某金属，调节变阻器， 当电压表的示数为某值时，电流表的示数恰好减小为零；再用波长为的单色光重复上述实验，当电压表的示数增加到原来的3倍时，电流表的示数又恰好减小为零。已知普朗克常数为h，真空中光速为c。该金属的逸出功为( )A. B. C. D. 答案：【答案】B【解析】根据光电效应方程Ekm=h-W0，及Ekm=eUc；当用波长为λ0的单色光照射，则有：h-W0=eUc，当用波长为的单色光照射时，则有：h-W0=3eUc，联立上式解得：W0=，故ACD错误，B正确；故选B。 1.He promised not to tell anybody about my ____(秘密)。2. （知识）is power.3.It is necessary for us to ask questions _______(礼貌地).4.Don’t leave your bike outside. Someone may _______(偷)it.5.She knew the ____ (重要性) of working hard and not just to do what she enjoyed.6.I couldn’t decide _____(是否) or not to go to the party.