Circuit fundamentals, component behaviour, and electrical safety.
Electronics Information measures your knowledge of electrical theory and electronic devices: how current, voltage and resistance relate, what components do in a circuit, how AC and DC differ, and which tools and safety practices belong to the trade. Many items are plain recall of terms; a meaningful share are short calculations using Ohm’s law and the power formula.
The section assumes no lab experience. It asks whether you have picked up the working vocabulary of electricity - the difference between a conductor and an insulator, what a fuse is for, what happens when a series circuit opens - and whether you can substitute numbers into two formulas correctly.
EI is not an AFQT subtest, but it is the gate for a large group of electronics and technical jobs, so a job-specific line score makes it worth real study time if you are aiming at those ratings.
Section 6 of 10 in our timed mock template. This subtest is not part of the AFQT; it feeds service component and line scores used for job qualification.
The shapes below are what our bank is written against, and what the section is built around. None of them are reproduced from the official test.
Specific, not generic: what the items in this topic test, and the one or two moves that solve most of them.
Know the two rules and their consequences. In series, current is the same everywhere and voltages add; in parallel, voltage is the same across branches and currents add. Adding more loads in parallel decreases total resistance and draws more total current, while adding loads in series increases resistance and dims everything. A short is simply a path of near-zero resistance, so current becomes enormous and protection devices open the circuit.
15 original questions in this topic set.
I = E over R, and P = E times I. Learn the triangle, not the seven variants: cover the quantity you want and the remaining two tell you the operation. Then sanity-check the magnitude. Twelve volts across four ohms is 3 amperes; if your arithmetic says 48, you multiplied when you should have divided. Keep power in watts and remember that a kilowatt is 1000 watts.
12 original questions in this topic set.
Be able to state each component’s job in one phrase: a resistor limits current, a capacitor stores charge in an electric field, an inductor stores energy in a magnetic field and opposes changes in current, a diode conducts one way, a transistor switches or amplifies, a fuse melts once, a circuit breaker resets. Colour codes and typical ratings appear as identification items.
13 original questions in this topic set.
DC flows in one direction from a source of constant polarity such as a battery; AC reverses direction periodically, and mains frequency is the number of those cycles per second. Know what a transformer does - it changes AC voltage, and it does nothing to steady DC - and the practical reasons AC is distributed: high voltage means lower current, and lower current means less loss in the line.
10 original questions in this topic set.
Match instrument to purpose: a voltmeter is connected across a circuit, an ammeter is placed in series with it, and an ohmmeter measures resistance only on a de-energised circuit. Safety items almost always favour the most conservative option - disconnect power first, verify it is dead, use ground-fault protection near water, and never remove a ground pin.
10 original questions in this topic set.
Sampled from the Electronics Information bank below, spread across its topics so you can see the range. The correct option is marked, the method is written out, and the tempting wrong options are explained - the same format you get in the app the moment you answer.
Two lamps are wired in series on a single loop across a battery, and one lamp's filament burns out. What happens to the other lamp?
A series circuit gives current only one path around the loop. When the burned-out filament opens that path, no current flows anywhere in the circuit, so the second lamp goes out too.
A 5-ohm resistor carries a current of 2 amperes. What is the voltage across it?
Ohm's law gives voltage as current times resistance: V = I × R = 2 × 5 = 10 volts.
Which electronic component stores energy in an electric field between two conducting plates?
A capacitor is two conductive plates separated by an insulator; it holds charge in the electric field between the plates and releases it when the circuit allows.
Which description fits direct current (DC)?
Direct current keeps a single direction of flow, with the source maintaining fixed polarity. Batteries, thermocouples, and DC power supplies are typical sources.
On the clock
EI is 16 items in 8 minutes, so about 30 seconds each. Definition items should take five seconds; reserve your time for the calculation items, and do those first if arithmetic slows you down, while your attention is fresh.
Free Electronics Information practice on this site, graded instantly with explanations. Timed sections, wrong-answer review and the full library are in the app.