Impedance and Admittance: Master AC Circuit Properties

Question 1

In an AC circuit, what is the relationship between impedance and admittance?

Accepted Answer

Complex conjugates of each other

Answer

Same units of measurement

Answer

Impedance measures opposition to current flow in DC circuits

Answer

Admittance measures power dissipation in a circuit

Question 2

In an AC circuit, how does an increase in impedance affect the current flow?

Accepted Answer

Decreases

Answer

Increases

Answer

Remains unchanged

Question 3

In AC circuits, how does impedance (Z) relate to resistance (R)?

Accepted Answer

Z is a complex quantity that includes both resistance and reactance.

Answer

Z is always equal to R, regardless of frequency.

Answer

Z is a constant value that does not change with frequency.

Question 4

The imaginary part of the impedance of an inductor represents:

Accepted Answer

Inductance

Answer

Resistance

Answer

Capacitance

Answer

Frequency

Question 5

The reciprocal of impedance is:

Accepted Answer

Admittance

Answer

Impedance angle

Answer

Power factor

Answer

Reactance

Question 6

In a series AC circuit, the total impedance is:

Accepted Answer

The sum of the individual impedances

Answer

The difference of the individual impedances

Answer

The product of the individual impedances

Answer

The quotient of the individual impedances

Question 7

Which AC circuit element typically has the highest impedance?

Accepted Answer

Inductor

Answer

Resistor

Answer

Capacitor

Answer

Diode

Question 8

The power dissipated in a purely inductive circuit is:

Accepted Answer

Zero

Answer

Positive

Answer

Negative

Answer

Imaginary

Question 9

The resonance frequency of a series RLC circuit occurs when:

Accepted Answer

Inductive reactance equals capacitive reactance

Answer

Inductive reactance is greater than capacitive reactance

Answer

Capacitive reactance is greater than inductive reactance

Answer

Impedance is at a maximum

Question 10

In the frequency domain, what is the impedance of a capacitor?

Accepted Answer

Z = 1 / jωC

Answer

Z = -jωL

Answer

Z = jwC

Answer

Z = -1 / jwL

Question 11

What is the phase angle of the admittance of an inductor?

Accepted Answer

-90°

Answer

0°

Answer

90°

Answer

180°

Question 12

Which unit is used to measure impedance?

Accepted Answer

Ohms

Answer

Siemens

Answer

Farads

Answer

Henrys

Question 13

How are impedance and current related in an AC circuit?

Accepted Answer

I = V / Z

Answer

Z = V / I

Answer

Z = I / V

Answer

I = Z / V

Question 14

Which of the following does NOT affect the impedance of a circuit?

Accepted Answer

Power factor

Answer

Frequency

Answer

Resistance

Answer

Capacitance

Question 15

What is the admittance of a parallel combination of a resistor and a capacitor?

Accepted Answer

Y = Y_R + Y_C

Answer

Y = Y_R - Y_C

Answer

Y = Y_R * Y_C

Answer

Y = Y_R / Y_C

Question 16

What is the impedance of a series combination of a resistor and an inductor?

Accepted Answer

Z = Z_R + Z_L

Answer

Z = Z_R - Z_L

Answer

Z = Z_R / Z_L

Answer

Z = Z_L / Z_R

Question 17

Which quantity is the reciprocal of impedance?

Accepted Answer

Admittance

Answer

Resistance

Answer

Conductance

Answer

Inductance

Question 18

In an AC circuit, impedance (Z) and admittance (Y) are inversely related. If the impedance of a circuit decreases, what happens to its admittance?

Accepted Answer

Increases

Answer

Decreases

Answer

Remains the same

Answer

The relationship between Z and Y is not linear

Question 19

In an AC circuit, which formula is used to calculate the impedance (Z) of a circuit element with resistance (R) and inductance (L)?

Accepted Answer

Z = R + jωL

Answer

Z = R - jωL

Answer

Z = R / jωL

Answer

Z = jωL - R

Question 20

In an AC circuit, how does impedance affect the voltage and current waveforms?

Accepted Answer

Impedance influences both voltage and current waveforms, affecting their amplitudes and phase shifts.

Answer

High impedance reduces voltage amplitude and increases current amplitude.

Answer

Low impedance increases voltage amplitude and decreases current amplitude.

Question 21

An inductor with an inductance of 2 mH and a resistor with a resistance of 100 ohms are connected in series. What is the impedance of the circuit?

Accepted Answer

100.5 ohms

Answer

98.0 ohms

Answer

102.0 ohms

Question 22

A circuit has an impedance of 10 + j5 ohms. Find the magnitude of the impedance.

Accepted Answer

11.18 ohms

Answer

12.0 ohms

Answer

10.5 ohms

Question 23

Which of the following is NOT a property of impedance?

Accepted Answer

It is independent of frequency.

Answer

It opposes the flow of alternating current.

Answer

It is a vector quantity.

Answer

It is measured in ohms.

Question 24

A circuit has an impedance of 5 + j3 ohms. What is the phase angle of the impedance?

Accepted Answer

31°

Answer

60°

Answer

45°

Answer

22°

Question 25

A circuit has a total impedance of 10 ohms and a total admittance of 0.1 S. Calculate the power factor of the circuit.

Accepted Answer

0.9

Answer

0.8

Answer

0.7

Answer

1.0

Question 26

What is an advantage of using complex impedance?

Accepted Answer

It simplifies AC circuit analysis.

Answer

It requires less mathematical knowledge.

Answer

It provides more accurate results.

Answer

It is easier to understand.

Question 27

The reciprocal of impedance is termed:

Accepted Answer

Admittance

Answer

Susceptance

Answer

Conductivity

Answer

Reactance

Question 28

The real and imaginary components of impedance are known as:

Accepted Answer

Resistance and Reactance

Answer

Capacitance and Inductance

Answer

Susceptance and Conductance

Answer

Phase Angle and Power Factor

Question 29

In a series AC circuit comprising a resistor, inductor, and capacitor, the total impedance is given by:

Accepted Answer

Z = R + j(XL - XC)

Answer

Z = XL + XC - jR

Answer

Z = j(XL + XC) - R

Answer

Z = R - j(XL - XC)

Question 30

In a parallel AC circuit with a resistor, inductor, and capacitor, the total admittance is calculated as:

Accepted Answer

Y = G + j(B - C)

Answer

Y = B + C - jG

Answer

Y = j(B + C) - G

Answer

Y = G - j(B - C)

Question 31

The power factor of an AC circuit is the ratio of:

Accepted Answer

Real Power to Apparent Power

Answer

Reactive Power to Apparent Power

Answer

Reactive Power to Real Power

Answer

Apparent Power to Real Power

Question 32

Determine the complex conjugate of the impedance Z = 5 + 3j.

Accepted Answer

5 - 3j

Answer

3 + 5j

Answer

3 - 5j

Answer

5 - 2j

Question 33

Identify the unit of admittance.

Accepted Answer

Siemens

Answer

Farads

Answer

Ohms

Answer

Henrys

Question 34

Which of the following factors does NOT affect the impedance of a circuit?

Accepted Answer

Voltage

Answer

Capacitance

Answer

Inductance

Answer

Resistance

Question 35

In an alternating current (AC) circuit, which of the following quantities represents the reciprocal of impedance?

Accepted Answer

Admittance

Answer

Susceptance

Answer

Reactance

Answer

Conductivity

Question 36

In an AC circuit, the complex power can be determined using which expression?

Accepted Answer

Voltage multiplied by the complex conjugate of the current

Answer

Apparent power multiplied by the power factor

Answer

Voltage multiplied by the current

Answer

Current multiplied by the impedance

Question 37

Which unit is used to measure admittance?

Accepted Answer

Siemens (S)

Answer

Henries (H)

Answer

Farads (F)

Answer

Ohms (Ω)

Question 38

For a series RLC circuit, the total impedance can be calculated using the formula:

Accepted Answer

√(R^2 + (ωL - 1/(ωC))^2)

Answer

R/(ωL - 1/(ωC))

Answer

R + ωL - 1/(ωC)

Answer

R - ωL + 1/(ωC)

Question 39

The power factor of an AC circuit is defined as:

Accepted Answer

Cosine of the phase angle (θ)

Answer

Sine of the phase angle (θ)

Answer

Tangent of the phase angle (θ)

Answer

Cotangent of the phase angle (θ)

Question 40

In a circuit with a power factor of 0.707, the relationship between real and reactive power is:

Accepted Answer

Equal real and reactive power

Answer

Less real power than reactive power

Answer

No reactive power

Answer

More real power than reactive power

Question 41

The resonance frequency of a series RLC circuit occurs when:

Accepted Answer

ω = 1/√(LC)

Answer

ω = LC

Answer

ω = 1/LC

Answer

ω = √(LC)

Question 42

Which of the following is the unit of impedance?

Accepted Answer

Ohms

Answer

Watts

Answer

Farads

Answer

Henries

Question 43

Admittance in an AC circuit is directly proportional to which of the following circuit element properties?

Accepted Answer

Conductance

Answer

Inductance

Answer

Resistance

Answer

Capacitance

Question 44

A resistor of 20 ohms and an inductor of 10 henries are connected in series. The impedance of the circuit when the frequency of the applied AC voltage is 50 Hz is:

Accepted Answer

22.36 ohms

Answer

14.14 ohms

Answer

6.32 ohms

Answer

9.12 ohms

Question 45

In an AC circuit, the phase angle between the voltage and current is determined by:

Accepted Answer

The ratio of reactance to resistance

Answer

The frequency of the applied voltage

Answer

The ratio of resistance to reactance

Answer

The amplitude of the applied voltage

Question 46

The power dissipated in a circuit element is a function of:

Accepted Answer

Current and voltage

Answer

Voltage only

Answer

Frequency only

Answer

Current only

Question 47

In a parallel RLC circuit, the resonant frequency occurs when:

Accepted Answer

Capacitive reactance equals inductive reactance

Answer

Capacitive reactance is greater than inductive reactance

Answer

Resistance is greater than inductive and capacitive reactance

Answer

Inductive reactance is greater than capacitive reactance

Question 48

A series RL circuit has an inductor with 10 mH inductance and a resistor. The circuit is driven by an AC voltage source with an angular frequency of 1000 rad/s. If the current through the circuit is 0.5 A, and the voltage drop across the resistor is 5 V, what is the resistance of the resistor?

Accepted Answer

10 Ω

Answer

20 Ω

Answer

15 Ω

Answer

5 Ω

Question 49

A parallel RC circuit has a capacitor with 100 μF capacitance and a resistor. The circuit is driven by an AC voltage source with an angular frequency of 1000 rad/s. If the current through the circuit is 1 A, and the voltage across the resistor is 100 V, what is the resistance of the resistor?

Accepted Answer

100 Ω

Answer

50 Ω

Answer

200 Ω

Answer

150 Ω

Question 50

A parallel RLC circuit has a resistor with 10 Ω resistance, an inductor with 10 mH inductance, and a capacitor with 100 μF capacitance. The circuit is driven by an AC voltage source with an angular frequency of 1000 rad/s. What is the total admittance of the circuit?

Accepted Answer

0.1 S

Answer

0.2 S

Answer

0.05 S

Answer

0.15 S

Question 51

A parallel RLC circuit has a resistor with 10 Ω resistance, an inductor with 10 mH inductance, and a capacitor with 100 μF capacitance. The circuit is driven by an AC voltage source with an angular frequency of 1000 rad/s. What is the power factor of the circuit?

Accepted Answer

0.707

Answer

1

Answer

0.866

Answer

0.5

Question 52

An inductor with 10 mH inductance and a capacitor with 100 μF capacitance are connected in series. The circuit is driven by an AC voltage source. What is the resonant frequency of the circuit?

Accepted Answer

1591.5 Hz

Answer

1000 Hz

Answer

2000 Hz

Answer

500 Hz