Question 1

Phasor algebra for sinusoidal quantities is applicable only for waveforms which have different frequencies.

Accepted Answer

Phasor algebra for sinusoidal quantities is applicable for waveforms that have the same frequency, allowing for the simplification of calculations involving sinusoidal functions in circuits.

Question 2

The length of a phasor is called the magnitude.

Accepted Answer

The length of a phasor represents its magnitude, which corresponds to the amplitude of the quantity (such as voltage or current) in sinusoidal functions.

Question 3

The length of a phasor represents the amplitude.

Accepted Answer

The length (or magnitude) of a phasor represents the amplitude of the sinusoidal function it represents in phasor notation.

Question 4

Determine the instantaneous value of a sine wave whose rms is 20 V, and phase angle is -297 degrees. 
A) -17.8 V 
B) -25.2 V
C) +17.8 V
D) +25.2 V

Accepted Answer

The answer of Determine the instantaneous value of a sine...

Question 5

The length of the phasor "arrow" represents the of a quantity.
A) amplitude
B) frequency
C) angle
D) direction

Accepted Answer

The length of the phasor "arrow" represents the amplitude of a quantity, indicating its magnitude in a phasor diagram.

Question 6

A phasor represents a time-varying quantity in terms of both magnitude and direction.

Accepted Answer

A phasor is a complex number used in engineering, especially in electricity and electronics, to represent a sinusoidal function whose amplitude (magnitude), angular frequency, and initial phase are time-invariant. It simplifies the analysis of systems with sinusoidal signals by representing them in terms of magnitude and phase angle (direction).

Question 7

The instantaneous value of a sine wave voltage, at any point, is equal to the vertical distance from the tip of the phasor to the:
A) horizontal axis
B) negative peak
C) positive peak
D) vertical axis

Accepted Answer

The instantaneous value of a sine wave voltage, at any point, is represented by the projection of the phasor on the vertical axis. This projection forms a right triangle with the vertical axis, where the vertical distance from the tip of the phasor to the horizontal axis corresponds to the instantaneous value of the sine wave.

Question 8

The time base control of the oscilloscope does which of the following?
A) adjusts the vertical scale
B) shows you the current time of day
C) sends a clock pulse to the probe
D) sets the amount of time represented by the horizontal width of the screen

Accepted Answer

The time base control of an oscilloscope sets the amount of time that is represented by the horizontal width of the screen, allowing users to adjust the display to view signals over different time intervals. This is crucial for analyzing the timing and duration of electrical signals.

Question 9

The equivalent negative angle for a positive angle of 30 degrees is:
A) 330 degrees
B) -330 degrees
C) -60 degrees
D) -150 degrees

Accepted Answer

The equivalent negative angle for a positive angle is found by subtracting the angle from 360 degrees. So, for a positive angle of 30 degrees, the equivalent negative angle is 360 - 30 = 330 degrees.

Question 10

In a circuit that contains a dc voltage source of 15 V and an ac voltage source of 50 Vp and a resistive load, what would be the maximum and minimum voltage measured across the resistive load?
A) VMAX = zero V, VMIN = 35 V
B) VMAX = 65 V, VMIN = zero V
C) VMAX = 35 V, VMIN = 65 V
D) VMAX = 65 V, VMIN = 35 V

Accepted Answer

The maximum voltage (VMAX) across the resistive load is the sum of the DC voltage and the peak AC voltage: 15 V + 50 V = 65 V. The minimum voltage (VMIN) is the DC voltage minus the peak AC voltage: 15 V - 50 V = -35 V, but since voltage cannot be negative across a resistive load, it is considered as 35 V.

Question 11

Phasors are a convenient graphic way of representing sine wave voltages in terms of their:
A) magnitude and frequency
B) magnitude and amplitude
C) magnitude and period
D) magnitude and phase

Accepted Answer

Phasors represent sine wave voltages by showing their magnitude and phase angle, which helps in analyzing AC circuits.

Question 12

The angular position of a phasor represents the amplitude of a sine wave.

Accepted Answer

The angular position of a phasor represents the phase of a sine wave, while its length represents the amplitude.

Question 13

Which of the following expresses angular velocity?
A) 2n/T
B) f/T
C) n/T
D) 2n × T

Accepted Answer

Angular velocity is expressed as 2π/T, where T is the period of rotation. The symbol π is approximately equal to 3.14159, and it is often represented by the letter n in simplified formulas. Therefore, 2n/T correctly represents angular velocity.

Question 14

The opposite side of a right triangle is equal to the hypotenuse times the sine of the angle 0.

Accepted Answer

In a right triangle, the side opposite to an angle θ is equal to the hypotenuse times the sine of that angle, expressed as $ \text{opposite} = \text{hypotenuse} \times \sin(\theta) $.

Question 15

The velocity of rotation is called:
A) the frequency
B) the angular velocity
C) the wavelength
D) the speed

Accepted Answer

The velocity of rotation is referred to as the angular velocity, which measures the rate of change of the angle of the object as it rotates, typically expressed in radians per second.

Question 16

What is the angular velocity of a phasor representing a sine wave with a frequency of 1.4 kHz?
A) 440 rad/s
B) 4398 rad/s
C) 8796 rad/s
D) 880 rad/s

Accepted Answer

The angular velocity (ω) is calculated using the formula ω = 2πf, where f is the frequency. For a frequency of 1.4 kHz, ω = 2π * 1400 = 8796 rad/s.

Question 17

The length of a phasor is represented by the formula v = Vpsin 0.

Accepted Answer

The length of a phasor is represented by the formula v = Vp, where Vp is the peak voltage.

Question 18

A four-pole generator has a rotation speed of 400 rps. Determine the frequency of the output voltage. 
A) 200 Hz 
B) 400 Hz
C) 800 Hz
D) 1600 Hz

Accepted Answer

The frequency of the output voltage in a generator is calculated using the formula: Frequency (f) = (Number of poles * Speed in revolutions per second) / 2. For a four-pole generator rotating at 400 rps, the frequency is (4 * 400) / 2 = 800 Hz.

Quiz 11: Introduction to Alternating Current and Voltage

Phasor algebra for sinusoidal quantities is applicable only for waveforms which have different frequencies.

The length of a phasor is called the magnitude.

The length of a phasor represents the amplitude.

Determine the instantaneous value of a sine wave whose rms is 20 V, and phase angle is -297 degrees.

The length of the phasor "arrow" represents the of a quantity.

A phasor represents a time-varying quantity in terms of both magnitude and direction.

The instantaneous value of a sine wave voltage, at any point, is equal to the vertical distance from the tip of the phasor to the:

The time base control of the oscilloscope does which of the following?

The equivalent negative angle for a positive angle of 30 degrees is:

In a circuit that contains a dc voltage source of 15 V and an ac voltage source of 50 Vp and a resistive load, what would be the maximum and minimum voltage measured across the resistive load?

Phasors are a convenient graphic way of representing sine wave voltages in terms of their:

The angular position of a phasor represents the amplitude of a sine wave.

Which of the following expresses angular velocity?

The opposite side of a right triangle is equal to the hypotenuse times the sine of the angle 0.

The velocity of rotation is called:

What is the angular velocity of a phasor representing a sine wave with a frequency of 1.4 kHz?

The length of a phasor is represented by the formula v = Vpsin 0.

A four-pole generator has a rotation speed of 400 rps. Determine the frequency of the output voltage.