Basic Qualification · B-005 Basic electronics and theory · B-005-011-008
Un transformateur survolteur dont le rapport de transformation du primaire au secondaire est de 1:5 fournit 50 milliampères à une charge. En supposant un rendement de 100 %, quel est le courant au primaire?
- A250 mA
- B2 500 mA
- C10 mA
- D0,25 mA
Correct answer: A — 250 mA. Question tirée de la banque officielle d'ISDE.
Why
With a 1:5 step-up transformer, the voltage increases five times, but to keep power constant at 100% efficiency, the current must drop by that same factor. 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