Updated: Dec 9, 2025 | Source: 2024-2028 Question Pool | Topic: E6D
E6D02E6D

What is the equivalent circuit of a quartz crystal?

Deep Dive: E6D02

The correct answer is A: Series RLC in parallel with a shunt C representing electrode and stray capacitance. What is the equivalent circuit of a quartz crystal is series RLC in parallel with a shunt C representing electrode and stray capacitance. Quartz crystals have series resonance and parallel capacitance. For amateur radio operators, this is important for oscillator knowledge. Understanding this helps when working with crystal oscillators.

Why Other Answers Are Wrong

Option B: Incorrect. Parallel RLC with C as parallel combination isn't correct - crystal is series RLC in parallel with shunt C. Parallel RLC isn't correct. Option C: Incorrect. Series RLC with C as parallel combination isn't correct - crystal is series RLC in parallel with shunt C. C as parallel combination isn't the structure. Option D: Incorrect. Parallel RLC with C as series combination isn't correct - crystal is series RLC in parallel with shunt C. Series combination isn't correct.

Exam Tip

Quartz crystal equivalent circuit = series RLC in parallel with shunt C (electrode/stray). Think 'Q'uartz 'C'rystal = 'S'eries 'R'LC 'P'arallel 'C'. Quartz crystals have series resonance and parallel capacitance. Not parallel RLC, not series with parallel C combination - just series RLC parallel shunt C.

Memory Aid

Quartz crystal equivalent circuit = series RLC in parallel with shunt C (electrode/stray). Think 'Q'uartz 'C'rystal = 'S'eries 'R'LC 'P'arallel 'C'. Quartz crystals have series resonance and parallel capacitance. Important for oscillator knowledge.

Real-World Example

The equivalent circuit of a quartz crystal: It's a series RLC in parallel with a shunt C representing electrode and stray capacitance. The series RLC represents the crystal's resonance, and the parallel C represents the electrode and stray capacitance. This is the equivalent circuit - series RLC parallel shunt C.

Source & Coverage

Question Pool: 2024-2028 Question Pool

Subelement: E6D

Reference: 2024-2028 Question Pool · E6 - Circuit Components

Key Concepts

Equivalent circuit Quartz crystal Series RLC Parallel with shunt C Electrode and stray capacitance

Verified Content

Question from the official FCC Extra Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the E6D topic.