As we know,
\(\mu=({\frac{γ}{2\pi}})Bo\)
where,
\(\mu\) = frequency
γ = g y ro magnetic ratio
Bo = magnetic field
as we know (γ/2π) for proton = 42.578 MHz.T-1
\(∴ \frac{for\,frequency\,60\,MH_z}{60\times10^6}\) = (42.578 x 106 s-1.T-1)x Bo
\(Bo=(\frac{60}{42.578})T=1.40917\) Tesla or Bo = 1.41 Tesla
or Bo = 14092.gauss (1 Tesla = 10000 gauss)
for frequency = 300 MHZ
300 x 106 s-1 = (42.578 x 106 s-1 T-1) x Bo
\(Bo = (\frac{300}{42.578})Tesla\)
Bo = 7.04589 Tesla
or Bo = 70459 gauss (∵ 1 Tesla = 10000 gauss)