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ASVAB Electronics Information practice test
10 free questions · scored as you go · every answer explained
Current, voltage and resistance, circuits, wiring and electronic devices. Key for technical ratings. On the computer-based ASVAB you get 15 Electronics Information questions in 10 minutes, about 40 seconds per question. It does not count toward your AFQT, but the services use it to qualify you for certain jobs.
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0/ 10
Practice scores from original questions, not official ASVAB scores. ASVAB Test is not affiliated with the U.S. Department of Defense.
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EIElectronics Information1 of 10
A 12-volt battery is connected across a 4-ohm resistor. How much current flows?
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Answer: D. 3 amperes
Ohm's law: I = V ÷ R = 12 ÷ 4 = 3 amperes. The triangle V = I × R rearranges to solve for any of the three quantities.
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EIElectronics Information2 of 10
Electrical resistance is measured in:
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Answer: B. Ohms
Resistance is measured in ohms (Ω). Volts measure electrical pressure, amperes measure current flow, and watts measure power.
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EIElectronics Information3 of 10
Which of these materials is the best conductor of electricity?
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Answer: C. Copper
Copper conducts electricity extremely well and is affordable, which is why household wiring is copper. Rubber, glass and dry wood are insulators that resist current flow.
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EIElectronics Information4 of 10
What is the purpose of a fuse in a circuit?
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Answer: D. To melt and break the circuit when current gets too high
A fuse contains a thin metal strip that melts when current exceeds its rating, opening the circuit before wiring overheats. A blown fuse must be replaced; a circuit breaker does the same job but can be reset.
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EIElectronics Information5 of 10
A 4-ohm and a 6-ohm resistor are connected in series. What is the total resistance?
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Answer: A. 10 ohms
In series, resistances simply add: 4 + 6 = 10 ohms. Current must pass through both, so each adds opposition. The 2.4-ohm figure would be the parallel combination.
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EIElectronics Information6 of 10
The current supplied by a battery is:
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Answer: C. Direct current (DC)
A battery's chemical reaction pushes current in one constant direction: direct current. Wall outlets supply alternating current, which reverses direction many times per second.
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EIElectronics Information7 of 10
A heater draws 5 amperes from a 120-volt outlet. How much power does it use?
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Answer: B. 600 watts
Power = voltage × current: 120 × 5 = 600 watts. P = VI is the power companion to Ohm's law.
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EIElectronics Information8 of 10
What does a capacitor do in a circuit?
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Answer: A. Stores electrical charge and releases it when needed
A capacitor holds charge on two plates separated by an insulator and releases it quickly when the circuit calls for it, like a camera flash. Transformers step voltage; resistors oppose current.
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EIElectronics Information9 of 10
In standard U.S. household wiring, the ground wire is usually:
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Answer: A. Green or bare copper
Ground wires are green or bare copper. Black (and sometimes red) wires are hot, carrying power; white is the neutral return. Mixing these up is dangerous.
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EIElectronics Information10 of 10
A diode allows current to flow:
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Answer: B. In one direction only
A diode is a one-way valve for current. That property makes diodes the building block of rectifiers, which convert AC to DC.
What Electronics Information covers
The facts and methods behind the questions, from the app's study notes. Questions on test day are different, but they test the same things.
Electrical basics
Electrical basics: Ohm’s law, power and energy, and what conducts, insulates or semiconducts.
- The two formulas. V = IR and P = VI (also P = I²R). 12 V across 4 Ω → 3 A. 120 V at 5 A → 600 W. Energy = power × time: a 2 kW heater for 3 h = 6 kWh.
- Units. Volts push (pressure), amperes flow (current), ohms resist, watts spend (power), hertz cycle (frequency). The water-pipe analogy: voltage = pressure, current = flow, resistance = narrowness.
- Materials. Copper and silver conduct; rubber and glass insulate; silicon semiconducts (and can be doped to switch — the basis of chips). Current in wires is moving electrons.
Circuits and components
Circuits and components: series versus parallel, schematic symbols, and what each component does.
- Series vs. parallel. Series: one path, same current everywhere, resistances add, one break kills all (old holiday lights). Parallel: same voltage on each branch, total resistance drops below the smallest — two 8 Ω in parallel = 4 Ω. Homes are parallel.
- Symbols. Zigzag = resistor; long/short lines = battery; two equal lines = capacitor; loops = inductor; triangle into a bar = diode. Ammeters wire in series; voltmeters in parallel.
- Components. Resistor opposes; capacitor stores charge (electric field); inductor stores magnetically; transformer changes AC voltage by its turns ratio (100:50 turns halves 120 V to 60 V); diode passes one way. Color code: brown-black-red = 1,000 Ω.
Practical electricity
Practical electricity: house wiring and safety, AC/DC and batteries, and everyday electronic devices.
- Wiring and safety. Black/red = hot, white = neutral, green/bare = ground. Switch the HOT wire. Fuses melt once; breakers reset; both stop overcurrent. GFCIs trip on milliamp leaks (kitchens, baths). Smaller AWG number = thicker wire = more current. A short circuit is a near-zero-resistance path — huge current, fire risk.
- AC, DC and batteries. Batteries make DC chemically; four 1.5 V cells in series = 6 V. US outlets: 120 V AC at 60 Hz. Generators induce voltage by moving conductors through magnetic fields.
- Devices. Rectifier: AC→DC (every charger). Inverter: DC→AC. Amplifier strengthens signals. Antennas radiate and catch radio waves; AM varies amplitude, FM varies frequency (FM shrugs off static).
Keep going in the app. All 50 Electronics Information questions, practice that brings back the ones you miss, and full exams timed subtest by subtest like the real test.
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These are original practice questions; real ASVAB items are confidential. Practice scores are estimates, not official ASVAB scores. ASVAB Test is not affiliated with the U.S. Department of Defense or any military branch.