6A78 - If capacitors of 3, 5, and 7 microfarad are connected in parallel, what is the total capacitance?
A.9 microfarad
B.15 microfarad
C.10 microfarad
D.3 microfarad
6A79 - How many capacitors of 400 volts and 2 microfarad each would be necessary to obtain a combination rated at 1600 volts and 1.5 microfarad?
B.12
A.10
C.14
D.16
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6A80 - If a turn in an inductor is shorted:
D.All of the above
A.There will be an decrease of induction
B.There will be a decrease of Q
C.There will be overheating with possible burnout
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6A81 - The relationship between the number of turns and the inductance of a coil may be expressed by:
A.The inductance varies approximately as the square of the number of turns
B.The inductance varies approximately as the square root of the number of turns
C.Both A & B
D.None of the above
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6A82 - The formula for determining the resonant frequency of a circuit when the inductance and capacitance are known is:
C.Both A & B
A.f = 1/(2 pi times the square root of LC)
B.f = 0.159/(the square root of LC)
D.None of the above
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6A83 - The formula for determining the wavelength when the frequency is known is:
D.All of the above
A.Wavelength = 300,000/ f kHz
B.Wavelength = 300,000,000/ f Hz
C.Wavelength = 300/ f MHz
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6A84 - The wavelength of the period of one complete cycle of a radio wave of 0.000,001 second is:
A.300 M
B.3000 M
C.30 M
D.70 cm
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6A85 - The efficiency of a radio device is:
B.The ratio of the useful power output to the power input
A.The ratio of the power input to the power output
C.The ratio of the minimum power output to the maximum power output
D.None of the above
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6A86 - What is the total impedance of a parallel capacitor and inductor with equal values of reactance?
D.B & C
A.Infinite total reactance
B.Zero total reactance
C.Parallel impedance is resistive and infinite
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6A87 - The total inductance of two coils in parallel without any mutual coupling is:
A.Equal to the product of the two inductances divided by their sum
B.The sum of the individual inductances
C.Zero
D.None of the above
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6A88 - What is the total reactance of a series AC circuit, with no resistance and equal inductance and capacitive reactances?
D.All of the above
A.The two reactances cancel being equal and opposite
B.Net impedance is purely resistive and contains no reactive component
C.The total reactance is zero at the resonant frequency
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6A89 - The total inductance of two coils in series without any mutual coupling is:
A.The sum of the individual inductances
B.The product of the individual inductances divided by their sum
C.Infinite
D.None of the above
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6A90 - One wave-length is:
C.A and B
A.The distance a wave will travel in the time for one cycle
B.Centimeter wavelength = 30,000 / frequency MHz
D.Neither A or B
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6A91 - In an AC circuit, a series inductance acting alone:
A.Causes the current to lag the applied voltage by 90 degrees
B.Causes the current to lead the applied voltage by 90 degrees
C.Causes the current to lag the applied voltage by 45 degrees
D.Causes the current to lead the applied voltage by 45 degrees
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6A2 - Weather information is commonly sent by radio in map form by one-way facsimile transmission. Two common parameters which must be set by the receiving station are:
D.Index of cooperation (IOC), and revolutions per minute (RPM)
A.Lines-per-inch (LPI), and primary scan direction (PSD)
B.Frequency shift (FS), and phase response pattern (PRP)
C.Black-mode signal (BMS), and frequency jitter tolerance (FJT)
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6A3 - 2182 kHz is the international radiotelephone distress frequency. It is also used for a calling channel. The authorized mode of emission is H3E (single-sideband full carrier). A3E (double-sideband full carrier) is only authorized for equipment:
A.Solely intended for distress and safety communications
B.Built and sold after the GMDSS implementation date
C.Built and sold before the GMDSS implementation date
D.Solely intended for ship-to-shore public correspondence
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6A4 - Ship's power is generated as 3-phase and is ungrounded. On a delta-wound transformer with 120 VAC line-to-line secondary, what is the voltmeter reading from line to ground:
D.Any of the above
A.Approx 67 volts for a normal balanced system with no faults
B.0 VAC for a system with that phase faulted to ground
C.120 VAC when another phase is faulted to ground
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6A5 - When passing through areas of static charge, high voltages can accumulate on antennas which are insulated from ground. What protects a connected receiver from damage?
D.Any combination of the above
A.Lightning arresters and suppressors
B.Protection diodes on receiver input
C.Capacitive coupling and static dissipative circuits
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6A6 - Vertical shipboard antennas for use in the MF band (410-525 kHz) are often fitted with top-hat loading sections. What is the purpose of these structures?
B.Permits a physically short antenna to appear electrically longer
A.Provides aerodynamic compensation for stress during high winds
C.Improves the near-field radiated pattern at the expense of the far-field pattern
D.Prevents salt build-up on antennas from shunting RF energy to ground
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6A7 - Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:
B.Modulation must be reduced to zero to eliminate sidebands
A.Antenna must be grounded to suppress spurious side-lobes
C.Voltage to the PA must be kept at half-value
D.Antenna current must be reduced to about 2.5 uA
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