Basic Qualification · B-005 Basic electronics and theory · B-005-008-004
Si un signal émis avec 200 watts de puissance est reçu à un niveau de "S9 plus 10 dB" au S-mètre, quelle sera la nouvelle lecture si la puissance est réduite à 20 watts?
- AS9 plus 3 dB
- BS9 moins 10 dB
- CS9 plus 5 dB
- DS9
Correct answer: D — S9. Question tirée de la banque officielle d'ISDE.
Why
Reducing power from 200 watts to 20 watts cuts the signal strength by a factor of ten, which equals a 10 decibel drop. The full explanation — and one for every question — is in Pro.
Practise this section
Basic electronics and theory is section B-005 of the Basic exam: The theory: Ohm's law, power, series and parallel circuits, AC and DC, frequency and wavelength, decibels, and the metric prefixes the exam leans on.
Drill B-005 — free, no account