A Radio Tuning Circuit Part A A radio can be tuned into a particular station fre
ID: 1782647 • Letter: A
Question
A Radio Tuning Circuit Part A A radio can be tuned into a particular station frequency by adjusting the capacitance in an L-C circuit. Suppose that the minimum capacitance of a variable capacitor in a radio is 4.11 pF What is the inductance L of a coil connected to this capacitor if the oscillation frequency of the L-C circuit is 1.58 MHz, corresponding to one end of the AM radio broadcast band, when the capacitor is set to its minimum capacitance? Express your answer in henrys to three significant figures. Hints Submit My Answers Give Up Part B The frequency at the other end of the broadcast band is 0.530 MHz. What is the maximum capacitance Cmax of the capacitor if the oscillation frequency is adjustable over the range of the broadcast band? Express your answer in farads to three significant figures. Hints Submit My Answers Give Up ContinueExplanation / Answer
PART A:
f = 1 [2••(L•C)]
1.58 ×10^6 = 1 [2••[L • (4.11×10^-12)]
(1.58 ×10^6) • [2••[L • (4.11×10^-12)] = 1
L = 1 { (4.11×10^-12) • [2••(1.58 ×10^6)]² }
L = 2.47 mH = 0.00247 Henrys
PART B:
f = 1 [2••(L•C)]
0.530 ×10^6 = 1 [2••[(2.47 ×10^-3) • C]
(0.530 ×10^6) • [2••[(2.47 ×10^-3) • C] = 1
C = 1 { (2.47 ×10^-3) • [2••(0.530 ×10^6)]² }
C = 36.526 pF = 36.53 ×10^-12 = 3.65 x 19^-11F