The frequency of the AC supply is 50 Hz . This means the angular frequency, ω, is calculated as: ω=2πf=2π×50=100π radians per second. The given 220 V is the Root Mean Square (RMS) value of the voltage. The peak (maximum) voltage, Vmax, is related to the RMS value by: Vmax=220√2. The general expression for an AC voltage is: V(t)=Vmax‌cos(ωt) Substituting the values we calculated: V(t)=220√2‌cos(100πt) Comparing with the options, we see that Option A: V(t)=220√2‌cos(100πt) is the correct answer.