As we know,

\(\mu=({\frac{γ}{2\pi}})Bo\)

where,

\(\mu\) = frequency

γ = g y ro magnetic ratio

B_{o} = magnetic field

as we know (γ/2π) for proton = 42.578 MH_{z}.T^{-1}

\(∴ \frac{for\,frequency\,60\,MH_z}{60\times10^6}\) = (42.578 x 10^{6} s^{-1}.T^{-1})x Bo

\(Bo=(\frac{60}{42.578})T=1.40917\) Tesla or B_{o} = 1.41 Tesla

or B_{o} = 14092.gauss (1 Tesla = 10000 gauss)

for frequency = 300 MHZ

300 x 10^{6} s^{-1} = (42.578 x 10^{6} s^{-1} T^{-1}) x Bo

\(Bo = (\frac{300}{42.578})Tesla\)

B_{o} = 7.04589 Tesla

or B_{o} = 70459 gauss (∵ 1 Tesla = 10000 gauss)