Reactance, Impedance,Resonance
Basic Qualification Question Bank for Amateur Radio Operator Certificate Examinations 12 June, 2014

Reactance

(C)

B-005-010-001 How does a coil react to AC?
A As the amplitude of the applied AC increases, the reactance increases
B As the frequency of the applied AC increases, the reactance decreases
C As the frequency of the applied AC increases, the reactance increases
D As the amplitude of the applied AC increases, the reactance decreases

(D)
B-005-010-002 How does a capacitor react to AC?
A As the frequency of the applied AC increases, the reactance increases
B As the amplitude of the applied AC increases, the reactance increases
C As the amplitude of the applied AC increases, the reactance decreases
D As the frequency of the applied AC increases, the reactance decreases

(C)
B-005-010-003 The reactance of capacitors increases as:
A applied voltage decreases
B frequency increases
C frequency decreases
D applied voltage increases

(C)
B-005-010-005 Capacitive reactance:
A increases as frequency increases
B increases with the time constant
C decreases as frequency increases
D applies only to series RLC circuits

(C)
B-005-010-006 Inductive reactance may be increased by:
A a decrease in the supplied current
B an increase in the applied voltage
C an increase in the applied frequency
D a decrease in the applied frequency

(B)
B-005-010-007 What property allows a coil wound on a ferrite core to mitigate the effects of an offending radio signal?
A High reactance at audio frequencies
B High reactance at radio frequencies
C Low reactance at radio frequencies
D Low reactance at audio frequencies

(B)
B-005-010-008 What property allows an RF bypass capacitor on an audio circuit to divert an offending radio signal?
A High reactance at audio frequencies
B Low reactance at radio frequencies
C High reactance at radio frequencies
D Low reactance at audio frequencies

(A)
B-005-010-009 What property allows an RF bypass capacitor to have little effect on an audio circuit?
A High reactance at low frequencies
B Low reactance at high frequencies
C High reactance at high frequencies
D Low reactance at low frequencies

(D)
B-005-010-010 What property allows an RF choke coil to have little effect on signals meant to flow through the coil?
A High reactance at low frequencies
B Low reactance at high frequencies
C High reactance at high frequencies
D Low reactance at low frequencies

(A)
B-005-010-011 In general, the reactance of inductors increases with:
A increasing AC frequency
B decreasing AC frequency
C decreasing applied voltage
D increasing applied voltage

Impedance

(D)

B-005-010-004 In inductances, AC may be opposed by both resistance of winding wire and reactance due to inductive effect. The term which includes resistance and reactance is:
A resonance
B inductance
C capacitance
D impedance

Resonance

(B)

B-005-012-001 Resonance is the condition that exists when:
A resistance is equal to the reactance
B inductive reactance and capacitive reactance are equal
C inductive reactance is the only opposition in the circuit
D the circuit contains no resistance

(A)
B-005-012-002 Parallel tuned circuits offer:
A high impedance at resonance
B low impedance at resonance
C zero impedance at resonance
D an impedance equal to resistance of the circuit

(B)
B-005-012-003 Resonance is an electrical property used to describe:
A the results of tuning a varicap(varactor)
B the frequency characteristic of a coil and capacitor circuit
C an inductor
D a set of parallel inductors

(A)
B-005-012-004 A tuned circuit is formed from two basic components. These are:
A inductors and capacitors
B resistors and transistors
C directors and reflectors
D diodes and transistors

(A)
B-005-012-005 When a parallel coil-capacitor combination is supplied with AC of different frequencies, there will be one frequency where the impedance will be highest. This is the:
A resonant frequency
B impedance frequency
C inductive frequency
D reactive frequency

(C)
B-005-012-006 In a parallel-resonant circuit at resonance, the circuit has a:
A low mutual inductance
B high mutual inductance
C high impedance
D low impedance

(A)
B-005-012-007 In a series resonant circuit at resonance, the circuit has:
A low impedance
B high impedance
C low mutual inductance
D high mutual inductance

(A)
B-005-012-008 A coil and an air-spaced capacitor are arranged to form a resonant circuit. The resonant
frequency will remain the same if we:
A add a resistor to the circuit
B increase the area of plates in the capacitor
C insert Mylar sheets between the plates of the capacitor
D wind more turns on the coil

(D)
B-005-012-009 Resonant circuits in a receiver are used to:
A filter direct current
B increase power
C adjust voltage levels
D select signal frequencies

(D) Resonance is the condition that exists when:
A inductive reactance is the only opposition in the circuit
B the circuit contains no resistance
C resistance is equal to the reactance
D inductive reactance and capacitive reactance are equal and opposite in sign

(C)

B-005-012-011 When a series LCR circuit is tuned to the frequency of the source, the:
A line current leads the applied voltage
B impedance is maximum
C line current reaches maximum
D line current lags the applied voltage
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