//Introductory Topics :example 1-5 : (pg no. 16)
k=(1.38*10^-23);
T=(27+273);
f=(4*10^6);
R=100;
x=sqrt(4*k*T*f*R);
// to convert degres to kelvin, add 273 to it
printf("\nen = sqrt(4kT.delta(f)R) \nen = %.8f Vrms",x);