Comprehensive preparation for the Armed Services Vocational Aptitude Battery
Understanding electrical principles and electronic components
The Electronics Information (EI) section of the ASVAB tests your knowledge of electrical principles, electronic components, circuits, and related terminology. This section evaluates your understanding of basic electronics concepts that are important for many military occupations, especially those in technical fields.
Test Format: On the CAT-ASVAB (computerized version), you'll have 8 questions to answer in 8 minutes. On the P&P-ASVAB (paper version), you'll have 20 questions to answer in 9 minutes. While this section doesn't contribute to your Armed Forces Qualification Test (AFQT) score, it is important for qualifying for certain technical military occupational specialties.
| Concept | Definition | Unit |
|---|---|---|
| Electric Charge | Fundamental property of matter that causes it to experience a force when placed in an electromagnetic field | Coulomb (C) |
| Current | Flow of electric charge (typically electrons) through a conductor | Ampere (A) |
| Voltage | Electric potential difference between two points, which drives current flow | Volt (V) |
| Resistance | Opposition to the flow of electric current | Ohm (Ω) |
Ohm's Law describes the relationship between voltage (V), current (I), and resistance (R):
This can be rearranged to:
Power is the rate at which electrical energy is transferred or converted:
Other power formulas:
| Circuit Type | Characteristics | Formulas |
|---|---|---|
| Series |
|
Rtotal = R₁ + R₂ + R₃ + ... |
| Parallel |
|
1/Rtotal = 1/R₁ + 1/R₂ + 1/R₃ + ... |
| Component | Function | Symbol | Unit |
|---|---|---|---|
| Resistors | Limit or control current flow | Zigzag line | Ohm (Ω) |
| Capacitors | Store and release electrical energy | Two parallel lines | Farad (F) |
| Inductors | Store energy in a magnetic field | Coil or series of loops | Henry (H) |
| Diodes | Allow current to flow in one direction only | Triangle pointing to a line | - |
| Transistors | Amplify or switch electronic signals | Various | - |
| Concept | Definition | Formula | Unit |
|---|---|---|---|
| Frequency | Number of cycles per second | f = 1/T | Hertz (Hz) |
| Period | Time for one complete cycle | T = 1/f | Seconds (s) |
| Capacitive Reactance | Capacitor's opposition to AC | XC = 1/(2πfC) | Ohm (Ω) |
| Inductive Reactance | Inductor's opposition to AC | XL = 2πfL | Ohm (Ω) |
| Concept | Description | Examples |
|---|---|---|
| Binary System | Base-2 number system (0 and 1) | 10102 = 1010 |
| Logic Gates | Perform logical operations | AND, OR, NOT, NAND, NOR, XOR |
Problem: A circuit has a voltage of 12 volts and a resistance of 4 ohms. What is the current flowing through the circuit?
Solution:
Answer: The current is 3 amperes.
Problem: Three resistors (5Ω, 10Ω, 15Ω) are connected in series. What is the total resistance?
Solution:
Answer: Total resistance is 30 ohms.
Problem: Two resistors (6Ω and 12Ω) are connected in parallel. What is the total resistance?
Solution:
Answer: Total resistance is 4 ohms.
Problem: A transformer has 500 turns in primary coil and 100 turns in secondary coil. Input voltage is 120V. What is output voltage?
Solution:
Answer: Output voltage is 24 volts.
Problem: Convert binary 1011 to decimal.
Solution:
Answer: Decimal equivalent is 11.
| Concept | Definition | Formula | Unit |
|---|---|---|---|
| Current (I) | Flow of electric charge | I = V/R | Ampere (A) |
| Voltage (V) | Electric potential difference | V = IR | Volt (V) |
| Resistance (R) | Opposition to current flow | R = V/I | Ohm (Ω) |
| Power (P) | Rate of energy transfer | P = VI | Watt (W) |
Pitfall: Using incorrect formula (e.g., V × R instead of V ÷ R)
Correction: I = V/R (not V × R)
Pitfall: Adding resistances in parallel (4Ω + 4Ω = 8Ω)
Correction: 1/(1/4Ω + 1/4Ω) = 2Ω
Pitfall: Treating AC like DC (ignoring reactance)
Correction: AC has both resistance and reactance
V
---
I R
Cover the variable you want to find. The remaining variables show the operation needed.
"Bad Boys Run Over Your Granny Because Vehicles Go Wrong"
Colors: Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Gray, White
This practice test contains 30 multiple-choice questions covering various aspects of electronics knowledge. Try to answer all questions within 8 minutes to simulate the time constraints of the actual ASVAB test.
What is the current in a circuit with a voltage of 12 volts and a resistance of 4 ohms?
Answer: A) 3 amperes
Using Ohm's Law: I = V/R = 12 volts / 4 ohms = 3 amperes
What is the resistance in a circuit with a voltage of 9 volts and a current of 3 amperes?
Answer: A) 3 ohms
Using Ohm's Law: R = V/I = 9 volts / 3 amperes = 3 ohms
How much power is consumed by a device that draws 2 amperes from a 6-volt source?
Answer: C) 12 watts
Using the power formula: P = V × I = 6 volts × 2 amperes = 12 watts
Which of the following materials is the best conductor of electricity?
Answer: C) Copper
Copper is a metal and an excellent conductor of electricity. Rubber, glass, and wood are insulators that resist the flow of electricity.
What happens to the resistance of a copper wire as its temperature increases?
Answer: B) Resistance increases
In most metals, including copper, resistance increases as temperature increases. This is because the increased thermal energy causes the atoms to vibrate more, which impedes the flow of electrons.
Review the explanations for each question to understand the correct answers.