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

$\begin{array}{1 1} 2.675 \times 10^6\;Hz \\ 26.75 \times 10^6\;Hz \\ 2.675 \times 10^7 Hz \\ 267.5 \times 10^6\;Hz \end{array}$