WBJEE 2025 Physics and Chemistry Papers

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.