5. The ratio of W/VA in an ac circuit means what?

Consider the following voltage divider circuit: 

Identify the circuit as either a high pass filter, low pass filter, band pass filter, band stop filter or none of the above. 

The circuit above, is known to exhibit a resonance at a frequency given by ω02=1/LC. Show that the 3dB bandwidth of the circuit around this resonance is given by δω3dB=R/L. 

A coil having an inductance of 6 H and an unknown resistance is connected in series with 
a resistor of 10 Ω to a 120 V dc supply. The time constant of the circuit is 300 ms. When 
steady state conditions have been reached, the supply is replaced instantaneously by a short-circuit. Determine the resistance of the coil, the current flowing in the circuit one second after the shorting link has been placed in the circuit, and the time taken for the current to fall to 10% of its initial value. 

A coil having an inductance of 6 H and an unknown resistance is connected in series with 
a resistor of 10 Ω to a 120 V dc supply. The time constant of the circuit is 300 ms. When 
steady state conditions have been reached, the supply is replaced instantaneously by a shortcircuit. Determine the resistance of the coil, the current flowing in the circuit one second 
after the shorting link has been placed in the circuit, and the time taken for the current to 
fall to 10% of its initial value