**Your
answer to Q190: **Sorry,
your answer is **not **correct. What can you vary to make two different-looking
waves out of sine waves at 200 and 400 Hz.

Help: *Fundamentals of
Sound*, Sec. 6-C.

Or, would you like a HINT?

You should really try to work out the answer on your own, but if you insist on reading it, the correct answer is HERE.

Return to Question
190.

**Hint
for Q190**: What the question means is that the two sine waves at 200
and 400 Hz are added with one relative phase for one total wave and then with
another relative phase to form another wave.

Return to Question 190.

**Your
answer to Q190: **Congratulations, your answer is **correct**!

To read the "official" correct answer, click HERE.

Return
to Question 190.

**Correct
answer to Q190**: The statement is false. Compare the two waves in Figs.
6-4 and 6-5 of *Fundamentals of Sound*. The only difference between the
two waves is that the 400 Hz wave has a different phase in the two figures.
However, the ear is unable to distinguish phase differences (this statement
is called Ohm's law) and the two wave forms sound the same.

Return
to Question 190.

**Your
answer to Q193: **Sorry, your answer is **not **correct. You need
to know the definition of "phase."

Help: *Fundamentals of
Sound*, Sec. 6-A.

Or, would you like a HINT?

You should really try to work out the answer on your own, but if you insist on reading it, the correct answer is HERE.

Return to Question
193.

**Hint
for Q193**: The left wave starts upward at *t *= 0 and the right
one starts down.

Return to Question 193.

**Your
answer to Q193: **Congratulations, your answer is **correct**!

To read the "official" correct answer, click HERE.

Return
to Question 193.

**Correct
answer to Q193**: The two waves are not in the same part of their cycles
at *t* = 0 or at any other times; when one is at a crest the other is at
a trough. They are said to be "180 degrees out of phase." The statement is false.

Return
to Question 193.

**Your answer to Q195: **Sorry, your answer is
**not **correct. What repeat time does a complex oscillatory wave have? What
is its reciprocal?

Help: *Fundamentals of
Sound*, Secs. 6-C, 7-B.

Or, would you like a HINT?

You should really try to work out the answer on your own, but if you insist on reading it, the correct answer is HERE.

Return to Question
195.

**Hint
for Q195**: Any complex repeating wave can be thought of being made
up of a harmonic series of sinusoidal waves. Which of these has the same period
as that of the complex wave?

Return to Question 195.

**Your
answer to Q195: **Congratulations, your answer is **correct**!

To read the "official" correct answer, click HERE.

Return
to Question 195.

**Correct
answer to Q195**: Any complex repeating wave can be thought of as being
made up of a harmonic series of sinusoidal waves added together with some set
of amplitudes. The repeat time of the complex wave is the same as the period
of the fundamental and its reciprocal is the frequency of the complex wave and
of the fundamental. When you take the reciprocal of the repeat time of the complex
wave, you immediately have the frequency of the fundamental. The frequencies
of all the other harmonics that make up the complex wave are multiples (*f*_{0},
2*f*_{0}, 3*f*_{0}, etc.) of this fundamental. In this way the statement
is true.

Return
to Question 195.

**Your
answer to Q200: **Sorry, your answer is **not **correct. This
question is based on what you learned in Chapter 2 about the harmonic series.

Help: *Fundamentals of
Sound*, Sec. 2-C, 6-D.

Or, would you like a HINT?

Return to Question
200.

**Hint
for Q200**: The frequency of the second harmonic is just twice that
of the first harmonic.

Return to Question 200.

**Your
answer to Q200: **Congratulations, your answer is **correct**!

To read the "official" correct answer, click HERE.

Return
to Question 200.

**Correct
answer to Q200**: If the frequency of the first harmomic is *f*_{0},
then that of the second harmonic is 2*f*_{0}. If, as this says,
the frequency of the first harmonic is one-half that of the second, then its
period must be twice as long. The statement is true. This question is relevant
to the discussion of Chapter 6 of *Fundamentals of Sound*, because we can
see that it takes the first harmonic the longest time of all the harmonics to
repeat itself. After the period of the fundamental, the second harmonic has
repeated itself twice, the third three times, etc. Thus a complex repeating
wave's repeat time must be the period of the fundamental.

Return
to Question 200.

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