basic question regarding resistor and capacitor series circuit

The voltage in a capacitor is proportional to its charge. So, it is proportional to the integral of the current.

The integral of cos(x) is sin(x), cos(x) is 90 degrees before sin(x). [cos(x) = sin(x+90°)] 

So, for AC, the current in a capacitor precedes its voltage (in steady state).

ya.but it is purely capacitive circuit ...what about RC circuit?

what effect does the resistor imparts on the circuit conceptually?

No, what I wrote is not about a purely capacitive circuit, it is only about the relationship of current and voltage in steady state in a capacitor. AC current and voltage in steady state in a capacitor always have a phase difference of 90°, it doesn't matter what other elements are there in the circuit. In a resistance, current and voltage are in phase.

The total voltage for the RC circuit is the result of the vectorial sum of the voltage in the resistance and the voltage in the capacitor. If the impedance of the capacitor is dominant, the phase diff. will be close to 90°. If the resistance is dominant, it will be close to 0°. If their impedances are equal, the phase difference will be 45°.

Or, if you prefer to see it in its trigonometric form, the Vrc = Vr + Vc = A*cos(x) + B*sin(x). So Vrc=C*sin(x+d), where C and d can be obtained from A and B.

http://www.education2000.com/demo/demo/btnchtml/sinplcos.htm

got it...thanks :-)

got it ...thanks :-)