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# Electronics Information Overview for ASVAB Power Practice Problems (page 2)

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Updated on Aug 24, 2011

1. c.   Not grounding an electrical device runs the risk of electrocution.
2. c.   60 Hz is the frequency of the alternating voltage, which is the type of voltage used in the United States.
3. c.   To determine the total resistance in a series circuit similar to the one presented, total resistance is equal to the sum of the individual resistors. Hence, the total resistance in this schematic would be R1 + R2 + R3 = 1,500 ohms.
4. b.   Metal in a microwave oven reflecting the microwave energy generated by the microwave's magnetron can be reflected back. The metal can also cause arcing and sparks from interaction with the microwaves.
5. b.   The total current is equal to the sum of the currents through each resistor. Therefore, 4A + 4A + 4A = 12A.
6. a.   FM stands for frequency modulation.
7. c.   This symbol in a schematic depicts a wire that does not join another.
8. c.   Electrical pressure results from a difference of electrical force between two points. Hence, voltage is what pushes electricity through a circuit.
9. c.   Coulomb's law describes the electrostatic force between electric charges.
10. c.   The total resistance (25Ω) is already known. Using Ohm's law to determine the voltage drop, we first solve for I, which gives the total current flowing through the circuit. Since the resistors are in series, the same amount of current flows through each resistor. Once I is known, Ohm's law again lets us solve for E across R1:
11. I = E/R = 48/25 = 1.92 A

E = IR = 1.92 × 10 = 19.2 V

12. a.   If a vacuum cleaner is rated at 1,200 watts and operates at 120 volts, it will draw 10 amps of current. The Power Law can be applied:
13. P = I × E; I = P ÷ E; I = 1,200 watts ÷ 120 volts; I = 10 amperes.

14. d.   The electronic term given to a unit of electromotive force is a volt.
15. b.   A loopstick antenna is optimized for frequencies below 300kHz. Parabolicshaped or dish antennas typically operate in the gigahertz range.
16. d.   The design of a corner reflector antenna includes a conductive sheet behind it to direct radiation in the forward direction, enhancing reception by increasing the directivity of the RF signals.
17. c.   In antenna design, the larger the diameter of the reflector, the greater the reception effectiveness of a directional antenna, also known as gain.
18. c.   The power in circuit A is one-half the power in B, so the current through A must be onehalf the current through B. If either circuit had no current flowing, there would be zero power dissipated.
19. b.   The image shown is a horn antenna.
20. c.   FM radio broadcasting, amateur radio, broadcast television, and commercial aircraft transmit on very high frequency (VHF). VHF bands use the 30–300 MHz frequency band.
21. c.   A tuning capacitor is used in a radio device to adjust the resonant frequency or tune a radio frequency.
22. b.   A transformer changes voltage and amperage.