# Extra Class Exam Question Pool

effective 7/01/2008 thru 6/30/2012

 Show: Unseen questions Weak questions Review questions Learned questions Incorrect answer choices

E5D: AC and RF energy in real circuits: skin effect; electrostatic and electromagnetic fields; reactive power; power factor; coordinate systems

E5D01: What is the result of skin effect?

As frequency increases, RF current flows in a thinner layer of the conductor, closer to the surface

As frequency decreases, RF current flows in a thinner layer of the conductor, closer to the surface

Thermal effects on the surface of the conductor increase the impedance

Thermal effects on the surface of the conductor decrease the impedance

E5D02: Why is the resistance of a conductor different for RF currents than for direct currents?

Because of skin effect

Because the insulation conducts current at high frequencies

Because of the Heisenburg Effect

Because conductors are non-linear devices

E5D03: What device is used to store electrical energy in an electrostatic field?

A capacitor

A battery

A transformer

An inductor

E5D04: What unit measures electrical energy stored in an electrostatic field?

Joule

Coulomb

Watt

Volt

E5D05: What is a magnetic field?

The region surrounding a magnet through which a magnetic force acts

Electric current through the space around a permanent magnet

The space between the plates of a charged capacitor, through which a magnetic force acts

The force that drives current through a resistor

E5D06: In what direction is the magnetic field oriented about a conductor in relation to the direction of electron flow?

In a direction determined by the left-hand rule

In the same direction as the current

In a direction opposite to the current

In all directions; omnidirectional

E5D07: What determines the strength of a magnetic field around a conductor?

The amount of current

The resistance divided by the current

The ratio of the current to the resistance

The diameter of the conductor

E5D08: What is the term for energy that is stored in an electromagnetic or electrostatic field?

Potential energy

Amperes-joules

Joules-coulombs

Kinetic energy

E5D09: What is the term for an out-of-phase, nonproductive power associated with inductors and capacitors?

Reactive power

Effective power

True power

Peak envelope power

E5D10: In a circuit that has both inductors and capacitors, what happens to reactive power?

It is repeatedly exchanged between the associated magnetic and electric fields, but is not dissipated

It is dissipated as heat in the circuit

It is dissipated as kinetic energy in the circuit

It is dissipated in the formation of inductive and capacitive fields

E5D11: How can the true power be determined in an AC circuit where the voltage and current are out of phase?

By multiplying the apparent power times the power factor

By dividing the reactive power by the power factor

By dividing the apparent power by the power factor

By multiplying the reactive power times the power factor

E5D12: What is the power factor of an R-L circuit having a 60 degree phase angle between the voltage and the current?

0.5

1.414

0.866

1.73

E5D13: How many watts are consumed in a circuit having a power factor of 0.2 if the input is 100-V AC at 4 amperes?

80 watts

400 watts

2000 watts

50 watts

E5D14: How much power is consumed in a circuit consisting of a 100 ohm resistor in series with a 100 ohm inductive reactance drawing 1 ampere?

100 Watts

70.7 Watts

141.4 Watts

200 Watts

E5D15: What is reactive power?

Wattless, nonproductive power

Power consumed in wire resistance in an inductor

Power lost because of capacitor leakage

Power consumed in circuit Q

E5D16: What is the power factor of an RL circuit having a 45 degree phase angle between the voltage and the current?

0.707

0.866

1.0

0.5

E5D17: What is the power factor of an RL circuit having a 30 degree phase angle between the voltage and the current?

0.866

1.73

0.5

0.577

E5D18: How many watts are consumed in a circuit having a power factor of 0.6 if the input is 200V AC at 5 amperes?

600 watts

200 watts

1000 watts

1600 watts

E5D19: How many watts are consumed in a circuit having a power factor of 0.71 if the apparent power is 500 watts?

355 W

704 W

252 W

1.42 mW

 Color key: ● = Unseen ● = Weak ● = Review ● = Learned ● = Incorrect answer
Home     What is ham radio?     Which exam to take?     Study tips     Where to take the exam?     Frequently Asked Questions (FAQ)     How to     How much math?     Trouble with practice exams     Feedback     Prices     Free Extra course for active volunteer examiners     Refund policy     Terms and conditions     Bumper sticker     Advertise with us     The Ham band     Rate us     Question pools     Course structure     Survivalists     Documents     facebook     Google+     Contact us     May Day Ham Radio!     Christina's story     TestOnline     Links