The magnetic field density applied in a cyclotron is $3.5 \;T$ what will be the frequency of electric field that must be applied between the dees in order to accelerate protons. Mass of protons $= 1.67 \times 10^{27}\;kg$

Question

$\begin{array}{1 1} 5.35 \times 10^7 \;Hz \\ 535 \times 10^7 \;Hz \\ 535 \times 10^7 \;Hz \\ 0.535 \times 10^7 \;Hz \end{array} $