用频率为ν的光照射某金属表面，恰好发生光电效应。现改用频率为2ν的光照射同一金属，则逸出光电子的最大初动能是（普朗克常量为h）
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Correct answer
A. hν
Principle or equation
爱因斯坦光电效应方程：E_kmax = hν - W₀，其中W₀为逸出功。恰好发生光电效应时，hν = W₀。
Why this answer is correct
频率为ν时恰好发生光电效应，说明逸出功W₀ = hν。改用频率2ν时，E_kmax = h(2ν) - hν = hν。
Example
若恰好发生光电效应的频率为ν₀，则用频率2ν₀的光照射，最大初动能为hν₀。
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