How to Determine the voltage polarity of inductor in a circuit?

[smatik]

The Voltage polarity across the inductor is same as that across the capacitor since both are in parallel and the voltage across them must be same.

But when Inductor, capacitor and resistor are connected as shown in the second figure what would be the voltage polarity across the inductor and why? (right end of inductor 'r'=+ve or -ve?)

 

[Baluncore]

The sum of the voltages around the circuit must be zero.
The battery causes a current to flow, the direction of flow sets the polarity of the components.

 

[smatik]

I've indicated The direction of current in second figure(Is it correct?). The current is due to charged capacitor(you can see the charge on the capacitor is Q). So what voltage equation would you write?

 

[Baluncore]

Your circuit diagram is confusing you. Redraw the diagram with the capacitor on the left (with positive terminal up), the resistor on the right and the inductor at the top. The bottom line is a reference voltage.

Energy from the capacitor on the left flows through the inductor to the resistor on the right where it is dissipated as heat.

Measuring around the circuit, VC + VL + VR = 0