Frequency of natural oscillation is given by, fn = {((dPe/dδ)at(δo))/M)} dPe/dδ = ((V1*V2)/X*(cosδ)) = (11/05)*cosδ = (11/0.5)*0.5 M = (H*s)/(πf) = 4/(50π)
In single phase energy meter, Current coil is made up from thick wire having few no. of turns. Pressure coil is made up from thin wire having more no. of turns.