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Subelement A
Principles
Section 7
Waveforms
What is a sine wave?
• A constant-voltage, varying-current wave.
A wave whose amplitude at any given instant can be represented by the projection of a point on a wheel rotating at a uniform speed.
• A wave following the laws of the trigonometric tangent function.
• A wave whose polarity changes in a random manner.

What is a sine wave?

A wave whose amplitude at any given instant can be represented by the projection of a point on a wheel rotating at a uniform speed.

Simply, sine wave is the fluctuation of voltage in a pattern that repeats over and over. It is a period oscillation of current. Light is a sine wave.

The sine wave can be plotted as a wave up and down on X-Y graph, or in a circle, as it goes up and down repeatedly.

For an excellent illustrated info and imbedded video, please see Electronics Notes site, for the article What is a Sine Wave - Electronics Waveform

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How many degrees are there in one complete sine wave cycle?
• 90 degrees.
• 270 degrees.
• 180 degrees.
360 degrees.

How many degrees are there in one complete sine wave cycle?

360 degrees.

Sine waves happen in AC current since it goes up and down in a cycle.

On an XY graph horizontal line, it starts first at 0 0 degrees, reaches the top at 90 0 degrees, drops back down to 0 0, which is 180 0degrees from 0 0 to 90 0 back to 0 0.

Then, the wave continues to -90 0 degrees, which would be 270 0 degrees total, and back to 0 0, which adds another 90 0 degrees to complete to 360 0 degrees.

For an excellent illustrated info and imbedded video, please see Electronics Notes site, for the article What is a Sine Wave - Electronics Waveform

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What type of wave is made up of sine waves of the fundamental frequency and all the odd harmonics?
Square.
• Sine.
• Cosine.
• Tangent.

What type of wave is made up of sine waves of the fundamental frequency and all the odd harmonics?

Square.

Though called continuous wave, CW, Morse Code signals are really square waves, as they have upper and lower points (on/off), a frequency and duration.

For great explanation, please see Electronics Notes site for the article on What is a Square Wave & Rectangular Waveform

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What is the description of a square wave?
• A wave with only 300 degrees in one cycle.
• A wave whose periodic function is always negative.
• A wave whose periodic function is always positive.
A wave that abruptly changes back and forth between two voltage levels and stays at these levels for equal amounts of time.

What is the description of a square wave?

A wave that abruptly changes back and forth between two voltage levels and stays at these levels for equal amounts of time.

Though called continuous wave, CW, Morse Code signals are really square waves, as they have upper and lower points (on/off), a frequency and duration.

For great explanation, please see Electronics Notes site for the article on What is a Square Wave & Rectangular Waveform

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What type of wave is made up of sine waves at the fundamental frequency and all the harmonics?
Sawtooth wave.
• Square wave.
• Sine wave.
• Cosine wave.

What type of wave is made up of sine waves at the fundamental frequency and all the harmonics?

Sawtooth wave.

This wave raises slowly to peak, then drops quickly. It refers to the increase and drop of the current, or movement of electrons (amperes).

NOTE Not to be confused with question 3-7A3 "... and all the odd harmonics?" which is the square wave.

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What type of wave is characterized by a rise time significantly faster than the fall time (or vice versa)?
• Cosine wave.
• Square wave.
Sawtooth wave.
• Sine wave.

What type of wave is characterized by a rise time significantly faster than the fall time (or vice versa)?

Sawtooth wave.

This wave raises slowly to peak, then drops quickly. It refers to the increase and drop of the current, or movement of electrons (amperes).