Advanced Qualification · A-003 Measurements · A-003-005-008
On applique un signal de 100 kHz à l'amplificateur horizontal d'un oscilloscope. On applique un signal de fréquence inconnue à l'amplificateur vertical. La forme d'onde qui en résulte comporte 5 boucles sur l'axe vertical et 2 boucles sur l'axe horizontal. La fréquence inconnue est :
- A50 kHz
- B30 kHz
- C40 kHz
- D20 kHz
Correct answer: C — 40 kHz. Question tirée de la banque officielle d'ISDE.
Why
The unknown frequency is 40 kHz because the oscilloscope shows a Lissajous pattern where the ratio of vertical loops to horizontal loops equals the ratio of the unknown frequency to the known 100 kHz signal. The full explanation — and one for every question — is in Pro.
Practise this section
Measurements is section A-003 of the Advanced exam: Measurements: meters, oscilloscopes, counters, signal generators, and what a reading actually tells you.
Drill A-003 — free, no account