ASVAB Electronics Information: format, key formulas and how to prepare
Last checked October 14, 2026 · Sources: Department of Defense What to Expect page, Fact Sheet and sample questions; Army and Air Force ASVAB pages
ASVAB Electronics Information (EI) tests your knowledge of electricity and electronics: current, circuits, devices and electronic systems. It isn’t part of the AFQT, but it feeds the electronics and maintenance job scores in the Army and Air Force, and some Coast Guard A-school requirements.
What Electronics Information tests
The Department of Defense describes Electronics Information as knowledge of electricity and electronics, in the Science and Technical domain. The Air Force lists the content as electrical current, circuits, devices and electronic systems. Expect questions on how current behaves, how to work out simple circuit values, what common components do, and basic electrical safety.
Format and timing
| Computer (CAT-ASVAB) | Paper (P&P-ASVAB) | |
|---|---|---|
| Scored questions | 15 | 20 |
| Time limit | 10 minutes (21 with tryouts) | 9 minutes |
| Average time per question | About 40 seconds | About 27 seconds |
| Go back and change answers | No | Yes, within this subtest |
Source: officialasvab.com What to Expect page and Fact Sheet, checked October 14, 2026. Time per question is our calculation.
Some prep books still show the computer version as 16 questions in 8 minutes; the Department of Defense’s current pages say 15 scored questions in 10 minutes. Either way the pace is quick, so formulas need to be second nature.
Where Electronics Information counts
| Branch | Job scores that use Electronics Information |
|---|---|
| Army | Electronics, General Maintenance and Mechanical Maintenance line scores |
| Air Force | Electronics MAGE score |
| Coast Guard | Some A-school composites; the 2021 Information Systems Technician example used MK+EI+GS |
Sources: goarmy.com, airforce.com and the U.S. Coast Guard (2021 A-school article), checked October 14, 2026.
See our Army, Air Force and Coast Guard score guides for the full combinations.
Key formulas and facts to know
| Concept | What to remember |
|---|---|
| Ohm’s law | Voltage = current × resistance (V = I × R) |
| Power | Power = voltage × current (P = V × I), measured in watts |
| Series resistors | Add them: 2 Ω + 3 Ω = 5 Ω |
| Two equal resistors in parallel | Half of one: two 6 Ω resistors give 3 Ω |
| Units | Volts (V), amperes (A), ohms (Ω), watts (W) |
| Conductors and insulators | Copper and aluminum conduct well; rubber, glass and plastic insulate |
Standard electrical relationships. Our selection.
AC, DC and safety basics
Direct current (DC) flows in one direction, as it does from a battery. Alternating current (AC) reverses direction many times a second; standard household outlets in the US supply AC at about 120 volts and 60 hertz. A diode lets current flow in only one direction, which is how AC can be turned into DC. A transistor can switch or amplify a signal.
It also helps to know basic electrical safety. Fuses and circuit breakers protect a circuit by opening it when the current gets too high: a fuse melts and must be replaced, while a breaker can be reset. A ground wire gives fault current a safe path, which is why many plugs have a third prong. Water and damaged insulation both raise the risk of shock, so circuits should be switched off before work begins.
Worked examples
These are our own practice problems, not real ASVAB questions.
- Current. A 12-volt battery is connected across a 4-ohm resistor. What current flows? I = V ÷ R = 12 ÷ 4 = 3 amperes.
- Power. A device draws 2 amperes from a 12-volt supply. How much power does it use? P = 12 × 2 = 24 watts.
- Series circuit. Resistors of 2, 3 and 5 ohms are connected in series. The total resistance is 10 ohms.
- Parallel circuit. Two 10-ohm resistors are in parallel. The total resistance is 5 ohms, less than either resistor alone.
- Components. Which component stores electrical charge? A capacitor. Which one opposes the flow of current? A resistor.
How to prepare for Electronics Information
Try the Department of Defense's free Electronics Information sample questions to see the level and style.
Ohm's law and the power formula solve a large share of calculation questions. Practice rearranging them until it's automatic.
Draw small series and parallel circuits and work out total resistance and current by hand.
Learn what common components do (resistors, capacitors, diodes, transistors, fuses, switches) and the units each uses.
The pace is under a minute per question, so finish with timed sets of 15 questions in 10 minutes.
No calculator is allowed, so practice the arithmetic by hand. Our free ASVAB resources page lists no-cost practice.
Mistakes that cost Electronics Information points
- Adding parallel resistors as if they were in series.
- Mixing up current, voltage and resistance in Ohm’s law.
- Confusing units, such as volts with watts.
- Skipping this subtest because it isn’t in the AFQT, then missing an electronics job’s minimum.
Common questions about ASVAB Electronics Information
How many questions are on ASVAB Electronics Information?
On the computer version, 15 scored questions in 10 minutes, or 21 minutes if tryout questions are added. On the paper version, 20 questions in 9 minutes.
Does Electronics Information count toward the AFQT?
No. It feeds job scores, not the AFQT.
What formulas do I need for ASVAB Electronics?
Ohm’s law (V = I × R) and the power formula (P = V × I) cover most calculation questions.
Which jobs need a good Electronics Information score?
In the Army, Electronics, General Maintenance and Mechanical Maintenance jobs. In the Air Force, Electronics jobs.
Can I use a calculator for the circuit questions?
No. You can’t use a calculator on any part of the ASVAB.
See also our General Science and Mathematics Knowledge guides, or go back to the ASVAB overview. MockTestPrep is independent and is not affiliated with the Department of Defense or any service branch.