When electromagnetic radiation falls on a photocell, electrons of mass \({m_{\text{e}}}\) are emitted, provided the frequency of the radiation is greater than \({f_{\text{0}}}\). What is the maximum speed of the electron when radiation of frequency \(f\) falls on the photocell?

A.     \(\sqrt {\frac{{2hf}}{{{m_{\text{e}}}}}} \)

B.     \(\sqrt {\frac{{2h(f - {f_0})}}{{{m_{\text{e}}}}}} \)

C.     \(\sqrt {\frac{{hf}}{{{m_{\text{e}}}}}} \)

D.     \(\sqrt {\frac{{h(f - {f_0})}}{{{m_{\text{e}}}}}} \)

B