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    FCC Commercial Element 3 Question Pool (approved 25 June 2009)

    Subelement A Principles: 8 Key Topics, 8 Exam Questions

Key Topic 1: Electrical Elements

3-1A1 The product of the readings of an AC voltmeter and AC ammeter is called:

     A. Apparent power.

     B. True power.

     C. Power factor.

     D. Current power.

    3-1A2 What is the basic unit of electrical power?

     A. Ohm.

     B. Watt.

     C. Volt.

     D. Ampere.

3-1A3 What is the term used to express the amount of electrical energy stored in an electrostatic field?

     A. Joules.

     B. Coulombs.

     C. Watts.

     D. Volts.

3-1A4 What device is used to store electrical energy in an electrostatic field?

     A. Battery.

     B. Transformer.

     C. Capacitor.

     D. Inductor.

-1A5 What formula would determine the inductive reactance of a coil if frequency and coil inductance are 3


     A. X = f L L

     B. X = 2f L L

     C. X = 1 / 2f C L

     D. X = 1 / R2+X2 L

3-1A6 What is the term for the out-of-phase power associated with inductors and capacitors?

     A. Effective power.

     B. True power.

     C. Peak envelope power.

     D. Reactive power.

    Answer Key: 3-1A1: A 3-1A2: B 3-1A3: A 3-1A4: C 3-1A5: B 3-1A6: D

2009 FCC Commercial Element 3 Question Pool (approved 25 June 2009) Page1

Key Topic 2: Magnetism

    3-2A1 What determines the strength of the magnetic field around a conductor?

     A. The resistance divided by the current.

     B. The ratio of the current to the resistance.

     C. The diameter of the conductor.

     D. The amount of current.

3-2A2 What will produce a magnetic field?

     A. A DC source not connected to a circuit.

     B. The presence of a voltage across a capacitor.

     C. A current flowing through a conductor.

     D. The force that drives current through a resistor.

3-2A3 When induced currents produce expanding magnetic fields around conductors in a direction that opposes

    the original magnetic field, this is known as:

     A. Lenz’s law.

     B. Gilbert's law.

     C. Maxwell’s law.

     D. Norton’s law.

3-2A4 The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:

     A. Eddy currents.

     B. Hysteresis.

     C. Permeability.

     D. Reluctance.

3-2A5 What is meant by the term “back EMF”?

     A. A current equal to the applied EMF.

     B. An opposing EMF equal to R times C (RC) percent of the applied EMF.

     C. A voltage that opposes the applied EMF.

     D. A current that opposes the applied EMF.

3-2A6 Permeability is defined as:

     A. The magnetic field created by a conductor wound on a laminated core and carrying current.

     B. The ratio of magnetic flux density in a substance to the magnetizing force that produces it.

     C. Polarized molecular alignment in a ferromagnetic material while under the influence of a magnetizing


     D. None of these.

    Answer Key: 3-2A1: D 3-2A2: C 3-2A3: A 3-2A4: D 3-2A5: C 3-2A6: B

2009 FCC Commercial Element 3 Question Pool (approved 25 June 2009) Page2

Key Topic 3: Materials

3-3A1 What metal is usually employed as a sacrificial anode for corrosion control purposes?

     A. Platinum bushing.

     B. Lead bar.

     C. Zinc bar.

     D. Brass rod.

3-3A2 What is the relative dielectric constant for air?

     A. 1

     B. 2

     C. 4

     D. 0

3-3A3 Which metal object may be least affected by galvanic corrosion when submerged in seawater?

     A. Aluminum outdrive.

     B. Bronze through-hull.

     C. Exposed lead keel.

     D. Stainless steel propeller shaft.

3-3A4 Skin effect is the phenomenon where:

     A. RF current flows in a thin layer of the conductor, closer to the surface, as frequency increases.

     B. RF current flows in a thin layer of the conductor, closer to the surface, as frequency decreases.

     C. Thermal effects on the surface of the conductor increase the impedance.

     D. Thermal effects on the surface of the conductor decrease the impedance.

    3-3A5 Corrosion resulting from electric current flow between dissimilar metals is called:

     A. Electrolysis.

     B. Stray current corrosion.

     C. Oxygen starvation corrosion.

     D. Galvanic corrosion.

    3-3A6 Which of these will be most useful for insulation at UHF frequencies?

     A. Rubber.

     B. Mica.

     C. Wax impregnated paper.

     D. Lead.

    Answer Key: 3-3A1: C 3-3A2: A 3-3A3: D 3-3A4: A 3-3A5: D 3-3A6: B

2009 FCC Commercial Element 3 Question Pool (approved 25 June 2009) Page3

Key Topic 4: Resistance, Capacitance & Inductance

    3-4A1 What formula would calculate the total inductance of inductors in series?

     A. L = L / L T12

     B. L = L + L T12

     C. L = 1 / L + L T12

     D. L = 1 / L x L T12

    3-4A2 Good conductors with minimum resistance have what type of electrons?

     A. Few free electrons.

     B. No electrons.

     C. Some free electrons.

     D. Many free electrons.

3-4A3 Which of the 4 groups of metals listed below are the best low-resistance conductors?

     A. Gold, silver, and copper.

     B. Stainless steel, bronze, and lead.

     C. Iron, lead, and nickel.

     D. Bronze, zinc, and manganese.

3-4A4 What is the purpose of a bypass capacitor?

     A. It increases the resonant frequency of the circuit.

     B. It removes direct current from the circuit by shunting DC to ground.

     C. It removes alternating current by providing a low impedance path to ground.

     D. It forms part of an impedance transforming circuit.

    3-4A5 How would you calculate the total capacitance of three capacitors in parallel?

     A. C = C+ C / C - C + C. T1 2123

     B. C = C + C + C. T123

     C. C = C+ C / C x C + C. T1 2123

     D. C = 1 / C+1 / C + 1 / C. T123

    3-4A6 How might you reduce the inductance of an antenna coil?

     A. Add additional turns.

     B. Add more core permeability.

     C. Reduce the number of turns.

     D. Compress the coil turns.