Electronics Engineering (ELEX) Board Practice Exam

For a tuned collector oscillator in a radio receiver, how is the frequency of oscillation calculated?

1. Using the capacitance and voltage across the inductor

2. Using the LC tuned circuit parameters

3. By adding L and C values

4. Using series resonance formula only

The correct answer is: Using the LC tuned circuit parameters

The frequency of oscillation in a tuned collector oscillator is determined by the parameters of the LC tuned circuit, which includes the inductance (L) and the capacitance (C) of the components involved in the tank circuit. The fundamental principle governing the oscillation frequency derives from the resonance condition established by this LC configuration. Specifically, the frequency is calculated using the formula: \[ f = \frac{1}{2\pi\sqrt{LC}} \] This equation clearly demonstrates the relationship between the inductance and capacitance, emphasizing that the frequency is inversely related to the square root of the product of these two elements. As the capacitance or inductance changes, the frequency of oscillation will shift accordingly. The other choices do not accurately capture the method for calculating the frequency of oscillation in this type of circuit. For instance, using the capacitance and voltage across the inductor is not relevant to the direct calculation of frequency. Similarly, merely adding the values of L and C or applying a series resonance formula would not yield the correct frequency for oscillation in a tuned collector oscillator. Thus, the choice reflecting the use of the LC tuned circuit parameters aligns correctly with the principles governing its function.