Question 1

A half-wave rectifier is connected to 277 V AC. What is the average DC voltage?&#10;A) 121.3&#10;B) 122.5&#10;C) 123.9&#10;D) 124.6

Accepted Answer

D

Question 2

The peak value of a sine wave is one-____ of the peak-to-peak value.&#10;A) fifth&#10;B) fourth&#10;C) third&#10;D) half

Accepted Answer

The peak value of a sine wave is half of the peak-to-peak value because the peak value is measured from the center line (or zero point) to the highest point of the wave, and the peak-to-peak value is measured from the highest point to the lowest point of the wave which is twice the distance from the center line to the highest point. Therefore, the peak value is half of the peak-to-peak value.

Question 3

The RMS (root-mean-____) value is also called the ____ value.&#10;A) square; AC/DC&#10;B) sine; AC/DC&#10;C) square; effective&#10;D) sine; effective

Accepted Answer

The RMS value is a measure of the effective value of an AC signal. It is calculated by taking the square root of the mean of the squared values of the waveform, hence it is also called the effective value. The term "sine" or "square" refers to the shape of the waveform, but the correct term to describe the RMS value is "effective". Therefore, choice C is the correct answer.

Question 4

Each complete waveform of 360 degrees is called a ____.&#10;A) wave number&#10;B) wavelength&#10;C) cycle&#10;D) frequency

Accepted Answer

A cycle is a complete waveform of 360 degrees. A wavelength is the distance between two corresponding points on adjacent cycles, but it is measured in distance rather than degrees. Wave number and frequency are related to the number of cycles per unit of distance or time, respectively, and are not equivalent to a complete waveform.

Question 5

An AC sine wave with an RMS value of 120 V is connected to a full wave rectifier. What is the average DC voltage?&#10;A) 70.7&#10;B) 108&#10;C) 120&#10;D) 169.7

Accepted Answer

The average DC voltage output of a full-wave rectifier is approximately 0.637 times the peak voltage of the AC input. The RMS value of the AC sine wave is given as 120V. To find the peak voltage, we use the relationship V_peak = V_RMS * sqrt(2), which gives us 120V * sqrt(2) ≈ 169.7V. Therefore, the average DC voltage is approximately 0.637 * 169.7V ≈ 108V.

Question 6

The number of complete cycles that occur in one second is called the ____.&#10;A) wavelength&#10;B) wave number&#10;C) period&#10;D) frequency

Accepted Answer

The number of complete cycles that occur in one second is known as frequency. The other options, such as wavelength, wave number, and period, are related to properties of waves but do not directly describe the number of cycles occurring in a given time period.

Question 7

A(n) ____ wave is one in which the voltage rises at a constant rate with respect to time.&#10;A) linear&#10;B) parabolic&#10;C) exponential&#10;D) logarithmic

Accepted Answer

A linear wave is one in which the voltage rises at a constant rate with respect to time. This means that the wave has a constant slope and is represented by a straight line on a graph.

Question 8

Square waves are generally produced by electronic devices called ____.&#10;A) rotators&#10;B) transformers&#10;C) voltaic cells&#10;D) oscillators

Accepted Answer

Square waves are typically produced by electronic devices called oscillators, which generate a periodic signal with a fixed frequency and amplitude. Rotators and transformers are not typically used to produce square waves, and while voltaic cells can generate electrical signals, they cannot produce a precise square wave shape.

Question 9

The most common of all AC waveforms is the ____ wave.&#10;A) square&#10;B) linear&#10;C) sine&#10;D) triangle

Accepted Answer

Sine waves are the most common AC waveform because they naturally occur in many electrical systems and devices, and they have a simple and easily recognizable shape. Square, linear, and triangle waves are less common in AC systems and are usually only used in specific applications.

Question 10

The pulses in pulsating direct current are often referred to as ____.&#10;A) ripple&#10;B) flicker&#10;C) oscillation&#10;D) brownouts

Accepted Answer

The pulses in pulsating direct current are commonly referred to as ripple.

Question 11

The sine wave reaches its peak positive voltage at ____ degrees.&#10;A) 90&#10;B) 180&#10;C) 270&#10;D) 360

Accepted Answer

The answer of The sine wave reaches its peak positive...

Question 12

Frequency is measured in ____.&#10;A) hertz&#10;B) ohms&#10;C) volts&#10;D) meters

Accepted Answer

The answer of Frequency is measured in ____.&#10;A) hertz&#10;B) ohms&#10;C)...

Question 13

The average value for a half-wave rectifier is the same as that of a full-wave rectifier.

Accepted Answer

The answer of The average value for a half-wave rectifier...

Question 14

The most common frequency in the United States and Canada is 50 (Hz).

Accepted Answer

The answer of The most common frequency in the United...

Question 15

A ____ permits voltage to be stepped up or down.&#10;A) resistor&#10;B) transformer&#10;C) capacitor&#10;D) battery

Accepted Answer

The answer of A ____ permits voltage to be stepped...

Question 16

The RMS value can be found by dividing the peak value by the square root of ____.&#10;A) 1.25&#10;B) 1.325&#10;C) 1.414&#10;D) 3

Accepted Answer

The answer of The RMS value can be found by...

Question 17

Alternating current waveforms are the same regardless of how the current is produced.

Accepted Answer

The answer of Alternating current waveforms are the same regardless...

Question 18

Average values of voltage and current are alternating current values.

Accepted Answer

The answer of Average values of voltage and current are...

Question 19

A sine wave has a maximum voltage of 138 V. What is the voltage after 78 degrees of rotation?&#10;A) 133.44&#10;B) 134.96&#10;C) 135.90&#10;D) 136.17

Accepted Answer

The answer of A sine wave has a maximum voltage...

Question 20

The peak-to-peak value is measured from the maximum value in the positive direction to the maximum value in the negative direction.

Accepted Answer

The answer of The peak-to-peak value is measured from the...

Deck 9: Alternating Current