Chapter 24 - Complex Numbers for AC Circuits - Grob's Basic Electronics 13th

Numbers on the horizontal axis are called: a. imaginary numbers. b. conjugate numbers. c. real numbers. d. complex numbers.

c

Numbers on the plus or minus j axis are called: a. imaginary numbers. b. conjugate numbers. c. real numbers. d. complex numbers.

a

A value of −j500 Ω represents: a. 500 Ω of inductive reactance. b. 500 Ω of capacitive reactance. c. 500 Ω of resistance. d. 500 Ω of conductance.

b

An inductive reactance of 20 Ω can be expressed as: a. +20 Ω . b. j220 Ω . c. −j20 Ω . d. + j20 Ω .

d

A series AC circuit consists of 10 Ω of resistance and 15 Ω of inductive reactance. What is the impedance of this circuit when expressed in polar form?: a. 15 Ω + j10 Ω . b. 18∠56.3° Ω . c. 18∠33.7° Ω . d. 25∠56.3° Ω .

b

An AC circuit has an impedance, Z, of 50∠−36.87° Ω. What is the impedance of this circuit when expressed in rectangular form?: a. 40 Ω − j30 Ω . b. 40 Ω + j30 Ω . c. 30 Ω + j40 Ω . d. 30 Ω − j40 Ω .

a

When adding or subtracting complex numbers, all numbers must be in: a. polar form. b. scientific notation. c. rectangular form. d. none of the above.

c

When multiplying complex numbers in polar form,: a. multiply the magnitudes and subtract the phase angles. b. multiply the magnitudes and add the phase angles. c. multiply the angles and add the magnitudes. d. multiply both the magnitudes and phase angles.

b

When dividing complex numbers in polar form,: a. divide the magnitudes and subtract the phase angles. b. divide the magnitudes and add the phase angles. c. divide the phase angles and subtract the magnitudes. d. divide both the magnitudes and phase angles.

a

What is the admittance, Y, of a parallel branch whose impedance is 200∠−63.43° Ω?: a. 5∠−63.43° mS . b. 5∠26.57° mS . c. 200∠63.43 mS . d. 5∠63.43 mS .

d

In complex numbers, j^2 corresponds to: a. 180° . b. −1 . c. −90° . d. both a and b.

d

Susceptance, B, is: a. the reciprocal of impedance. b. the reciprocal of reactance. c. the reciprocal of resistance. d. the same as conductance.

b

A branch current of +j250 mA represents: a. 250 mA of inductive current. b. 250 mA of resistive current. c. 250 mA of capacitive current. d. 250 mA of in-phase current.

c

A parallel AC circuit has an admittance, YT, of 6 mS + j8 mS. What is the impedance, Z, in polar form?: a. 10∠45° kΩ . b. 100∠53.13° Ω . c. 100∠−53.13° Ω . d. 14∠53.13° Ω .

c

What is the resistance, R, of an AC circuit whose impedance, Z, is 300∠53.13° Ω?: a. 240 Ω . b. 180 Ω . c. 270 Ω . d. 60 Ω .

b