Basic Qualification · B-005 Basic electronics and theory · B-005-011-001
A transformer with a 120-volt primary voltage supplies 250 watts to a transmitter. Neglecting losses, what is the approximate primary current?
- A 3.1 amperes
- B 2.1 amperes
- C 0.48 amperes
- D 1.4 amperes
Correct answer: B — 2.1 amperes. From the official ISED question bank, verified word for word.
Why
To find the current flowing into the transformer, you divide the power used by the voltage supplied. The full explanation — and one for every question — is in Pro.
Practise this section
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.