Deck 25: Complex Numbers for Ac Circuits

Question 1

It is a lot less work to multiply and divide complex numbers that are in ______________ form.

Answer 1

polar

Question 2

In polar coordinates, the phase angle θ is ______________ from the 0° axis.

Answer 2

counterclockwise

Question 3

If series impedances are in polar form, they must be converted to ______________ form to be added.

Answer 3

rectangular

Question 4

In general, the reciprocal of an angle in polar form is the same angle with ______________ sign.

Question 5

The reciprocal of impedance is ______________.

Question 6

The reciprocal of reactance is ______________.

Question 7

______________ numbers refer to a numerical system that includes the phase angle of a quantity with its magnitude.

Question 8

Complex numbers are useful in ac circuits when the reactance makes it necessary to consider the ______________ angle.

Question 9

The angle of rotation is the ______________ for the number.

Question 10

An angle of 90° or +j is used for ______________ reactance.

Question 11

When multiplying or dividing complex numbers, it is a lot less work when these numbers are in the

A) rectangular form
B) polar form
C) algebraic form
D) phasor form

Question 12

When dividing a real number by an imaginary number, the converting of the denominator to a real number is called

A) equalization
B) rationalization
C) neutralization
D) ratio and proportion

Question 13

In electrical terms the complex impedance (4 + j3) means

A) 4 ? of R and 3 ? of X_L with a leading phase angle of 90°
B) 4 ? of R and 3 ? of X_C with a leading phase angle of 90°
C) 4 ? of X_L and 3 ? of R with a lagging phase angle of 90°
D) 4 ? of X_C and 3 ? of R with a lagging phase angle of 90°

Question 14

Magnitude-phase angle form is also called

A) rectangular coordinates
B) polar coordinates
C) imaginary number coordinates
D) real number coordinates

Question 15

What would an ammeter read when the circuit current is 5 at 37° A?

A) 5 A
B) 5 mA
C) 37 mA
D) 537 mA

Question 16

In polar coordinates, the distance from the center is the

A) phase angle of the phasor
B) magnitude of the phasor
C) resistive part of the phasor
D) reactive part of the phasor

Question 17

When complex numbers in polar form are to be added or subtracted, they must be

A) converted to rectangular form
B) converted to phasor form
C) added or subtracted in polar notation
D) added or subtracted algebraically

Question 18

In general, the reciprocal of an angle in polar form is

A) a different angle with same sign
B) a different angle with opposite sign
C) the same angle with same sign
D) the same angle with opposite sign

Question 19

What is the reciprocal of reactance?

A) Admittance
B) Susceptance
C) Reluctance
D) Acceptance

Question 20

A numerical system that includes the phase angle of a quantity with its magnitude is

A) binary
B) negative numbers
C) complex numbers
D) decimal

Question 21

The operator for -1 is

A) 45°
B) 90°
C) 180°
D) 360°

Question 22

The operator for a number can be any angle between

A) 0° and 90°
B) 0° and 180°
C) 90° and 270°
D) 0° and 360°

Question 23

In mathematics, numbers on the horizontal axis are

A) real numbers
B) imaginary numbers
C) binary numbers
D) octal numbers

Question 24

In mathematics, numbers on the j axis are called

A) real numbers
B) imaginary numbers
C) binary numbers
D) octal numbers

Question 25

The combination of a real and imaginary term is called a

A) negative number
B) binary number
C) complex number
D) integer number

Question 26

The number 3 + j4 is what form of complex numbers?

A) Polar
B) Rectangular
C) Phasor
D) Algebraic

Question 27

If the j term and the real term are equal, the angle is

A) 45°
B) 90°
C) 180°
D) 360°

Question 28

An angle of 0° is used for

A) R
B) X_L
C) X_C
D) Z

Question 29

An angle of ?90° is used for

A) R
B) X_L
C) X_C
D) Z

Question 30

Complex numbers refer to a numerical system that includes the phase angle of a quantity with its magnitude.

Question 31

Complex numbers are useful in ac circuits when the reactance of X_L or X_C makes it necessary to consider the phase angle.

Question 32

Generally, only dc circuits can be analyzed with complex numbers.

Question 33

In their more general form, numbers have both quantity and phase angle.

Question 34

To represent a negative number the angle of rotation or operator is 180°.

Question 35

The operator for a number can be any angle between 180° and 270°.

Question 36

The j is usually written before a number because the j sign is a 90° operator.

Question 37

In mathematics, numbers on the horizontal axis are real numbers and numbers on the j axis are called imaginary numbers.

Question 38

A resultant phasor extends from the tail of the first phasor to the arrowhead of the second.

Question 39

The combination of a real and an imaginary term is called a complex number.

Question 40

The number j3 is the same as j³.

Question 41

If the j term and the real term are equal, the angle is 45°.

Question 42

An angle of 0° or a real number without any j operator is used for inductive reactance.

Question 43

An angle of -90° or -j is used for X_C.

Question 44

The general form of stating impedance is Z = R ± jX.