Answer the following questions about the sharpness of resonance in a radio-frequency series LCR circuit:
a. (i) Define the quality factor Q of a series LCR circuit.
b. (ii) Explain, with the help of a suitable relation, how the bandwidth of the resonance curve depends on Q.
c. (iii) Give reasons why a high value of Q improves selectivity in a radio receiver but may simultaneously reduce its sensitivity.
d. (iv) Suggest one practical method by which a designer can control (increase or decrease) the value of Q in a tuning circuit and state the effect this would have on the bandwidth.