Really sorry for my shortcoming, here is all about my praticalHmmm, you are missing some crucial information. What resistor? What capacitor?
You need to show a circuit diagram.
What is the value of the resistor and the value of the capacitor?
The phase angle is a function of frequency. What is the frequency?
How much calculus background do you have?
What is the derivative of a cosine function?
Thanks for your answer, I tried to find more information in Basic Engineering circuit but cant find anything appropriate. I will find more about your suggestThe simple answer is that capacitor takes time to charge. Resistor is simply passing some current through, as soon as there is current flowing through the resistor, you have voltage across resistor. So voltage across resistor is establishing at the speed of current flowing through it, fast in other words. Capacitor does not work that way. Read the physics of the capacitor, it should be in a textbook that discusses physical composition of capacitor and the mechanics of capacitor operation.