What is enery density equation?

you showed that w=2Pif

but in equation you showed

(Aw)²=2Pi²F² A² please explain why 2 instead of 4

Energy Density is described as the amount of energy stored in a region or system per unit volume. Electric and magnetic fields can store energy. Energy density is denoted by using the letter U. In the case of electric field (capacitor), formula for energy density is,
U = ½₀ \varepsilono E2
In the case of magnetic field (inductor), energy density formula is,
U = B2 / 2 \mu0
In the case of electromagnetic waves, both electric and magnetic field contribute to energy density. So the formula for energy density becomeS the sum of the energy density of electric and magnetic field.