Electronics Engineering (ELEX) Board Practice Exam

What component primarily determines the frequency in an LC oscillator?

1. Capacitance

2. Inductance

3. Resistors

4. Transistors

The correct answer is: Inductance

The frequency in an LC oscillator is primarily determined by the combination of inductance and capacitance; however, the inductance plays a crucial role in defining the resonant frequency of the oscillator circuit. In an LC oscillator, the resonant frequency (f) can be calculated using the formula: \[ f = \frac{1}{2\pi \sqrt{LC}} \] where L is the inductance and C is the capacitance. From this relationship, it's clear that the inductance value is critical because it contributes directly to determining how fast the current oscillates through the inductor and capacitor. A higher inductance results in a lower resonant frequency, while a lower inductance results in a higher frequency, given a constant capacitance. While the capacitance also influences the frequency, the inductance is often considered the more dominant factor in many designs, especially where the inductor's characteristics significantly impact the circuit behavior. Therefore, in the context of LC oscillators, inductance is the primary component governing the oscillation frequency.