So we have a pretty simple circuit, just a 10V voltage source in series with an impedance of 1.8k ohms and a capacitor with a capacitance of 100nF. We're asked to check the voltage across the capacitor at various frequencies.
I was told we use the reactance of the capacitor to find the voltage, which is
1/wC. I do (what i thought was) a simple voltage division across the capacitor, which I thought was just
V * Xc/(Xc + R) with Xc being the reactance of the capacitor and R being the impedance of the other element.
The answers I get make sense but the solutions say that I should have used this formula:
V * Xc / sqrt(Xc^2 + R^2). the answers I get using either formula are both similar but why would I use that second formula? Where'd they get that from?