A beam of electrons is accelerated from rest through a potential difference \(V\). The de Broglie wavelength of the electrons is \(\lambda \). For electrons accelerated through a potential difference of \(2V\) the de Broglie wavelength is

A.     \(2\lambda \)

B.     \(\sqrt {2\lambda } \)

C.     \(\frac{\lambda }{2}\)

D.     \(\frac{\lambda }{{\sqrt 2 }}\)

D