Exam Primer

# 5.10 Reactance and Impedance

## Practice

B-005-10-01
How does a coil react to AC?
As the amplitude of the applied AC increases, the reactance decreases
As the amplitude of the applied AC increases, the reactance increases
As the frequency of the applied AC increases, the reactance increases
As the frequency of the applied AC increases, the reactance decreases

B-005-10-02
How does a capacitor react to AC?
As the frequency of the applied AC increases, the reactance decreases
As the frequency of the applied AC increases, the reactance increases
As the amplitude of the applied AC increases, the reactance increases
As the amplitude of the applied AC increases, the reactance decreases

B-005-10-03
The reactance of capacitors increases as:
applied voltage increases
AC frequency decreases
applied voltage decreases
AC frequency increases

B-005-10-04
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:
resonance
inductance
impedance
capacitance

B-005-10-05
Capacitive reactance:
decreases as frequency increases
applies only to series RLC circuits
increases as frequency increases
increases with the time constant

B-005-10-06
Inductive reactance may be increased by:
a decrease in the applied frequency
a decrease in the supplied current
an increase in the applied voltage
an increase in the applied frequency

B-005-10-07
A choke coil of 4.25 microhenrys is used in a circuit at a frequency of 200 MHz. Its reactance is approximately:
5 740 ohms
5 340 ohms
7 540 ohms
4 750 ohms

B-005-10-08
The capacitive reactance of a 25 microfarad capacitor connected to a 60 hertz line is:
106.1 ohms
9 420 ohms
2.4 ohms
1 500 ohms

B-005-10-09
A power-supply filter has a capacitor of 10 microfarad. What is the capacitive reactance of this capacitor to a frequency of 60 hertz?
200 ohms
100 ohms
500 ohms
265 ohms

B-005-10-10
What is the approximate inductive reactance of a 1 henry choke coil used in a 60 hertz circuit?
376 ohms
3760 ohms
188 ohms
1888 ohms

B-005-10-11
In general, the reactance of inductors increases with:
increasing AC frequency
decreasing AC frequency
decreasing applied voltage
increasing applied voltage