In the picture bellow there's capacitor connected to AC voltage. Phase of voltage is known and it's value is θ. Effective values of charge is Q and period is T (both are considered as known values). Find the expression for current i(t). Directions of current and voltage are shown in the picture.
Now, this is very easy problem, since I=Q/T it means that i have effective value of current. Now i only need it's phase, since passive element is capacitor it means that current is π/2 "ahead" of voltage so it's phase should be φ=θ+π/2 so
i(t)=Qsqrt(2)/T cos(ωt+θ+π/2). But if i look at the picture the direction of current opposes direction of voltage, does it means that this is not the correct phase of current, because, as far as i know, it works this way if directions are the same?
Now, this is very easy problem, since I=Q/T it means that i have effective value of current. Now i only need it's phase, since passive element is capacitor it means that current is π/2 "ahead" of voltage so it's phase should be φ=θ+π/2 so
i(t)=Qsqrt(2)/T cos(ωt+θ+π/2). But if i look at the picture the direction of current opposes direction of voltage, does it means that this is not the correct phase of current, because, as far as i know, it works this way if directions are the same?