A circuit has a voltage of 12 volts and a resistance of 4 ohms. According to Ohm's Law, what is the current flowing through the circuit?

Correct answer: 3 amperes. Ohm's Law solves for current as I = V / R. Plug in: I = 12 V / 4 Ω = 3 A. The answer is 3 amperes. Choice A (0.33 A) inverts the formula and computes R / V = 4 / 12. Choice C (8 A) subtracts instead of dividing (12 minus 4). Choice D (48 A) multiplies V by R, which is the calculation for a totally different relationship and ignores that current is voltage divided by resistance, not the product.

In a series circuit with three light bulbs, one bulb burns out. What happens to the other two bulbs?

Correct answer: They also go out.. A series circuit has one continuous loop, so current must pass through every bulb. When one filament opens, the loop breaks and current stops everywhere. All remaining bulbs go dark. Choice A (brighter) confuses series with parallel, where losing one branch can shift current. Choice B (normal operation) describes parallel wiring, where each bulb sits on its own independent path. Choice D (flicker but stay on) imagines a partial connection, but an open filament is a hard break, not an intermittent contact.

They continue operating normally.

What unit is used to measure electrical resistance?

Correct answer: Ohm. Resistance is measured in ohms, symbol Ω. The four core electrical units pair one-to-one: volts measure voltage (electrical pressure), amperes measure current (flow rate of charge), watts measure power (energy per second), and ohms measure resistance (opposition to flow). Choice A (volt) confuses resistance with the driving voltage from Ohm's Law. Choice B (ampere) confuses it with the current that resistance opposes. Choice C (watt) measures power dissipated in a resistor, not the resistance itself.

Which component in an electrical circuit allows current to flow in only one direction?

Correct answer: Diode. A diode is a semiconductor with a p-n junction that conducts when forward-biased and blocks current when reverse-biased, giving it one-way behavior. Rectifier bridges use this to turn AC into DC. Choice A (resistor) opposes current in both directions equally and is not polarity-sensitive. Choice B (capacitor) stores charge on plates and passes AC while blocking steady DC, but it has no preferred direction. Choice D (transformer) steps AC voltage up or down through induction and does not rectify direction at all.

A 60-watt light bulb operates on a 120-volt circuit. What is the current drawn by the bulb?

Correct answer: 0.5 amperes. Use P = I × V and solve for current: I = P / V = 60 W / 120 V = 0.5 A. The bulb draws 0.5 amperes. Choice A (0.25 A) divides by 240 or applies the formula twice. Choice C (2 A) inverts the division and computes V / P = 120 / 60. Choice D (7,200 A) multiplies power by voltage (60 × 120), which has no physical meaning here because the power formula calls for division when current is unknown, not multiplication.

What is the purpose of a fuse in an electrical circuit?

Correct answer: Protect the circuit by breaking if current exceeds a safe level. A fuse contains a thin metal strip rated for a specific current. When current exceeds that rating, the strip melts and opens the circuit, cutting power before wires overheat or components burn. Choice A (increase voltage) describes a transformer or boost converter, not a protective device. Choice B (store charge) describes a capacitor, which holds energy on plates. Choice D (regulate AC frequency) describes oscillator or inverter circuitry. A fuse only opens; it does not modify voltage, store energy, or shape waveforms.

Regulate alternating current frequency

Two resistors of 6 ohms each are connected in parallel. What is the total resistance of the combination?

Correct answer: 3 ohms. Parallel resistance uses 1/Rt = 1/R1 + 1/R2 = 1/6 + 1/6 = 2/6, so Rt = 3 Ω. Shortcut for equal parallel resistors: divide one by the count, 6 / 2 = 3 Ω. Choice A (12 Ω) adds them as if in series. Choice B (6 Ω) leaves resistance unchanged, missing that parallel paths reduce total resistance. Choice D (1 Ω) misapplies the formula by computing 1/(1/6 + 1/6) incorrectly or treating the reciprocal sum as the answer instead of inverting it.

Which material is the BEST electrical conductor?

Correct answer: Copper. Copper has a sea of loosely bound free electrons, giving it very low resistivity (about 1.7 × 10⁻⁸ Ω·m), which is why nearly all household wiring uses it. Choice A (rubber) is the classic insulator used for wire jackets, with resistivity many orders of magnitude higher. Choice B (glass) is an insulator used on power-line standoffs. Choice D (wood) is an insulator when dry. Mistaking any insulator for a conductor reverses the basic distinction between materials that pass current freely and materials that block it.

A transformer has 100 turns on its primary coil and 400 turns on its secondary coil. If the primary voltage is 120 volts, what is the secondary voltage?

Correct answer: 480 volts. Transformer turns ratio: Vs / Vp = Ns / Np. Plug in: Vs = 120 V × (400 / 100) = 120 × 4 = 480 V. More secondary turns means a step-up transformer. Choice A (30 V) inverts the ratio (100/400) and steps down instead of up. Choice B (120 V) ignores the ratio entirely. Choice D (600 V) multiplies primary voltage by 5 instead of 4, possibly by adding turns wrong or using (Np + Ns)/Np. The ratio is secondary over primary, not their sum.

How many free Electronics Information practice questions are here?

This page has 9 free ASVAB Electronics Information questions, each with the correct answer and a full worked explanation. They're free to use with no account required.

Does Electronics Information count toward my AFQT score?

No. Electronics Information is not one of the four AFQT subtests, so it does not affect your AFQT/enlistment score. It does feed line scores that determine which military jobs you qualify for.

What does the Electronics Information subtest cover?

Covers electrical circuits, components, and systems. Critical for electronics, IT, and technical military jobs across all branches. On the CAT-ASVAB it has 15 questions with about 10 minutes to answer them. Topics include: Circuits, Ohm's law, components, electrical safety.

Are these the same as the real ASVAB questions?

No. These are original practice questions calibrated to match the style and difficulty of the real ASVAB. The actual test is a secure exam, so no one publishes its live items. Practicing this format is the closest legitimate prep.

Free ASVAB Electronics Information Practice Test

9 Electronics Information (EI) practice questions, each with a worked explanation of the right answer.

Last updated May 2026

The ASVAB Electronics Information (EI) subtest covers circuits, Ohm's law, components, electrical safety. On the computer-adaptive CAT-ASVAB it has 15 questions with about 10 minutes to answer. It is not an AFQT subtest, but it feeds the line scores that decide which jobs you qualify for. Work the 9 questions below, then read each explanation. Understanding why the answer is right is what raises your score.

Question 1· Electronics Information
A circuit has a voltage of 12 volts and a resistance of 4 ohms. According to Ohm's Law, what is the current flowing through the circuit?
- A.0.33 amperes
- B.3 amperes
- C.8 amperes
- D.48 amperes
Show answer & explanationHide answer
Correct answer: B. 3 amperes
Why: Ohm's Law solves for current as I = V / R. Plug in: I = 12 V / 4 Ω = 3 A. The answer is 3 amperes. Choice A (0.33 A) inverts the formula and computes R / V = 4 / 12. Choice C (8 A) subtracts instead of dividing (12 minus 4). Choice D (48 A) multiplies V by R, which is the calculation for a totally different relationship and ignores that current is voltage divided by resistance, not the product.
Question 2· Electronics Information
In a series circuit with three light bulbs, one bulb burns out. What happens to the other two bulbs?
- A.They burn brighter.
- B.They continue operating normally.
- C.They also go out.
- D.They flicker but stay on.
Show answer & explanationHide answer
Correct answer: C. They also go out.
Why: A series circuit has one continuous loop, so current must pass through every bulb. When one filament opens, the loop breaks and current stops everywhere. All remaining bulbs go dark. Choice A (brighter) confuses series with parallel, where losing one branch can shift current. Choice B (normal operation) describes parallel wiring, where each bulb sits on its own independent path. Choice D (flicker but stay on) imagines a partial connection, but an open filament is a hard break, not an intermittent contact.
Question 3· Electronics Information
What unit is used to measure electrical resistance?
- A.Volt
- B.Ampere
- C.Watt
- D.Ohm
Show answer & explanationHide answer
Correct answer: D. Ohm
Why: Resistance is measured in ohms, symbol Ω. The four core electrical units pair one-to-one: volts measure voltage (electrical pressure), amperes measure current (flow rate of charge), watts measure power (energy per second), and ohms measure resistance (opposition to flow). Choice A (volt) confuses resistance with the driving voltage from Ohm's Law. Choice B (ampere) confuses it with the current that resistance opposes. Choice C (watt) measures power dissipated in a resistor, not the resistance itself.
Question 4· Electronics Information
Which component in an electrical circuit allows current to flow in only one direction?
- A.Resistor
- B.Capacitor
- C.Diode
- D.Transformer
Show answer & explanationHide answer
Correct answer: C. Diode
Why: A diode is a semiconductor with a p-n junction that conducts when forward-biased and blocks current when reverse-biased, giving it one-way behavior. Rectifier bridges use this to turn AC into DC. Choice A (resistor) opposes current in both directions equally and is not polarity-sensitive. Choice B (capacitor) stores charge on plates and passes AC while blocking steady DC, but it has no preferred direction. Choice D (transformer) steps AC voltage up or down through induction and does not rectify direction at all.
Question 5· Electronics Information
A 60-watt light bulb operates on a 120-volt circuit. What is the current drawn by the bulb?
- A.0.25 amperes
- B.0.5 amperes
- C.2 amperes
- D.7,200 amperes
Show answer & explanationHide answer
Correct answer: B. 0.5 amperes
Why: Use P = I × V and solve for current: I = P / V = 60 W / 120 V = 0.5 A. The bulb draws 0.5 amperes. Choice A (0.25 A) divides by 240 or applies the formula twice. Choice C (2 A) inverts the division and computes V / P = 120 / 60. Choice D (7,200 A) multiplies power by voltage (60 × 120), which has no physical meaning here because the power formula calls for division when current is unknown, not multiplication.
Question 6· Electronics Information
What is the purpose of a fuse in an electrical circuit?
- A.Increase voltage to components
- B.Store electrical charge
- C.Protect the circuit by breaking if current exceeds a safe level
- D.Regulate alternating current frequency
Show answer & explanationHide answer
Correct answer: C. Protect the circuit by breaking if current exceeds a safe level
Why: A fuse contains a thin metal strip rated for a specific current. When current exceeds that rating, the strip melts and opens the circuit, cutting power before wires overheat or components burn. Choice A (increase voltage) describes a transformer or boost converter, not a protective device. Choice B (store charge) describes a capacitor, which holds energy on plates. Choice D (regulate AC frequency) describes oscillator or inverter circuitry. A fuse only opens; it does not modify voltage, store energy, or shape waveforms.
Question 7· Electronics Information
Two resistors of 6 ohms each are connected in parallel. What is the total resistance of the combination?
- A.12 ohms
- B.6 ohms
- C.3 ohms
- D.1 ohm
Show answer & explanationHide answer
Correct answer: C. 3 ohms
Why: Parallel resistance uses 1/Rt = 1/R1 + 1/R2 = 1/6 + 1/6 = 2/6, so Rt = 3 Ω. Shortcut for equal parallel resistors: divide one by the count, 6 / 2 = 3 Ω. Choice A (12 Ω) adds them as if in series. Choice B (6 Ω) leaves resistance unchanged, missing that parallel paths reduce total resistance. Choice D (1 Ω) misapplies the formula by computing 1/(1/6 + 1/6) incorrectly or treating the reciprocal sum as the answer instead of inverting it.
Question 8· Electronics Information
Which material is the BEST electrical conductor?
- A.Rubber
- B.Glass
- C.Copper
- D.Wood
Show answer & explanationHide answer
Correct answer: C. Copper
Why: Copper has a sea of loosely bound free electrons, giving it very low resistivity (about 1.7 × 10⁻⁸ Ω·m), which is why nearly all household wiring uses it. Choice A (rubber) is the classic insulator used for wire jackets, with resistivity many orders of magnitude higher. Choice B (glass) is an insulator used on power-line standoffs. Choice D (wood) is an insulator when dry. Mistaking any insulator for a conductor reverses the basic distinction between materials that pass current freely and materials that block it.
Question 9· Electronics Information
A transformer has 100 turns on its primary coil and 400 turns on its secondary coil. If the primary voltage is 120 volts, what is the secondary voltage?
- A.30 volts
- B.120 volts
- C.480 volts
- D.600 volts
Show answer & explanationHide answer
Correct answer: C. 480 volts
Why: Transformer turns ratio: Vs / Vp = Ns / Np. Plug in: Vs = 120 V × (400 / 100) = 120 × 4 = 480 V. More secondary turns means a step-up transformer. Choice A (30 V) inverts the ratio (100/400) and steps down instead of up. Choice B (120 V) ignores the ratio entirely. Choice D (600 V) multiplies primary voltage by 5 instead of 4, possibly by adding turns wrong or using (Np + Ns)/Np. The ratio is secondary over primary, not their sum.

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What's on the ASVAB Electronics Information subtest

Covers electrical circuits, components, and systems. Critical for electronics, IT, and technical military jobs across all branches.

Common topics you'll see:

Ohm's law (V = IR)
Series & parallel circuits
Electrical components (resistors, capacitors, diodes)
AC vs DC current
Electrical safety & grounding
Basic digital electronics
Wiring & schematics
Power calculations (watts)
Magnetism & electromagnetism

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FAQ

How many free Electronics Information practice questions are here?: This page has 9 free ASVAB Electronics Information questions, each with the correct answer and a full worked explanation. They're free to use with no account required.
Does Electronics Information count toward my AFQT score?: No. Electronics Information is not one of the four AFQT subtests, so it does not affect your AFQT/enlistment score. It does feed line scores that determine which military jobs you qualify for.
What does the Electronics Information subtest cover?: Covers electrical circuits, components, and systems. Critical for electronics, IT, and technical military jobs across all branches. On the CAT-ASVAB it has 15 questions with about 10 minutes to answer them. Topics include: Circuits, Ohm's law, components, electrical safety.
Are these the same as the real ASVAB questions?: No. These are original practice questions calibrated to match the style and difficulty of the real ASVAB. The actual test is a secure exam, so no one publishes its live items. Practicing this format is the closest legitimate prep.

Free practice tests for the other subtests

ASVAB score calculator for converting raw scores to AFQT and line scores
Score requirements by branch for army, navy, air force, marines, and coast guard