alternating current Questions

An inductor of inductance $L$, a capacitor of capacitance $C$ and a resistor of resistance $R$ are connected in series to an ac source of potential difference $V$ volts. Potential difference across $L,C$ and $R$ is $40\text{V},10\text{V}$ and $40\text{V}$, respectively. The amplitude of current flowing through LCR series circuit is $10\sqrt{2}$. The impedance of the circuit is:

A series LCR circuit containing $5.0\text{H}$ inductor, $80\mu \text{F}$ capacitor and $40\Omega$ resistor is connected to $230\text{V}$ variable frequency ac source. The angular frequencies of the source at which power transferred to the circuit is half the power at the resonant angular frequency are likely to be:

A step down transformer connected to an ac mains supply of $220\text{V}$ is made to operate at $11\text{V},44\text{W}$ lamp. Ignoring power losses in the transformer, what is the current in the primary circuit?