A radio can tune over the frequency range of a portion of the MW broadcast band: (from to ). If its LC circuit has an effective inductance of , what must be the range of its variable capacitor?
Step 1: Given data
Step 2: The capacitance of the LCR circuit
Step 3: Finding the range of the capacitor
As we know the angular frequency of an LCR circuit is .
So,
Now, the capacitance of the variable capacitor for frequency and angular frequency is
And, the capacitance of the variable capacitor for frequency and angular frequency is
From equations 1 and 2 we get,
Therefore, the range of its variable capacitor is .