Question

1.)Two sound waves with same frequency overlap. Crests overlap with crests. Troughs overlap with troughs. The two sound waves are ( )
a.)In-phase
b.)Out-of-phase
c.)Out-of-synchronicity
d.)In-synchronicity

2.)If you want to build a destructive interference between two sound waves, you will need to set up the phase of these two sound waves ( )
a.)In-phase by π
b.)Largely different in frequency
c.)Slightly different in frequency
d.)Out-of-phase by π/2

3.)If two sound waves are constructive with each other, which statement is true for the outcome of superposition from these two waves? ( )
a.)The resultant frequency is the double frequency of each wave
b.)The resultant amplitude is zero
c.)The resultant frequency is smaller than the frequency for each wave
d.)The resultant amplitude is double amplitude for each wave

4.)Which wave behavior is used by your noise cancelling headphone?
a.)Destructive Interference
b.)Refraction
c.)Constructive Interference
d.)Diffraction

5.)If a sound wave has frequency 500 Hz, what is the period of this sound wave?
a.)0.005 seconds
b.)1 second
c.)0.002 seconds
d.)0.01 seconds

6.)Calculate the beat frequency if a 400 Hz and a 397 Hz sound are heard by a student
a.)2 Hz
b.)3 Hz
c.)1 Hz
d.)4 Hz

7.)If two sound waves have slightly different frequencies, they will result in which kind of interference pattern ( )
a.)Destructive Interference
b.)Constructive Interference
c.)Beats

8.)The high or low pitch of a sound is related to the ___________ of the wave.
a.)Frequency
b.)Rest Position
c.)Phase
d.)Amplitude

9.)If the pitch of a sound wave is increased, does the time period between waveforms increase or decrease?
a.)Random changes
b.)Remain the same
c.)Increase
d.)Decrease

10.)Two speakers are placed 500 meters away from each other. A person stands right in the middle of the two speakers. One of the speakers sends a sound wave traveling at 343m/s towards the person standing in the middle and the other speaker sends a sound wave traveling at 342m/s. How long after the person in the middle hears the first sound wave will he hear the second wave ( ) (please answer the question with unit of seconds)

Answer 1

1)

When the 2 sound waves of equal frequency are overlaps,ie interfere,Since the crust of the first wave overlaps with the crust of the second wave and the trough of the first wave overlap with the trough of the second wave indicating that there s no angle difference or the phase difference between the 2 waves,which lead them the overlap in this manner(constructive interference)

So,since there is no phase difference between the 2 waves,they are in phase.

(In phaseOption A)

2)

For the destructive interference is to take place between two wavws,the crust of one wave should overlaps with the trough of other and the trough of other should overlaps with the crust of the wave.

So,in the crust of a wave it comes thr trough of the other wave,So,the phase differene between the crust and trough is .

So,for destructive interference,they sound waves should be out of phase by

Out of phase by (Option d)

3)

If the sound identical sound waves undergo the constructive interfence the crust of the wave overlap with crust of other,and the trough of one wave overlaps with the trough of other.So,the resulting waves should have the amplitude is the sum of amplitudes of these two waves.So,for the case of identical sound waves of same amplitude undergo constructive interfernce,the resulting wave have amplitude double of each waves.

Alos there is no change happen in other parameters like frequency,wavelengh...

The resulting ampitude is double the aplitude of each waves(option d)

4)

The noise cancelling headphones uses the destructive interference to cancels the unwanted lower frequency noise waves by generating the waves of exactly negetive of the noise waves with the same frequency and oppsite phase by .So,they overlaps with the crust of the noise with the trough of the wave,causes destructive interfence will destroy the noise.

Destructive interference(option A)

5)

We have the time period of the sounwave,

So,here the frequency of sound wave,

So,time period,

Option C

6)

We have the beat freqency is the difference in the frequency of the sounds,

Here frequency of 1st wave,

Frequency of 2nd wave,

So,Beat frequency,

Option B

7)

if the 2 wave have slight difference in the frequencies between them,ie,

the Beats will occurs.

Option C

8)

The pitch of sound is related to th frequency of the sound.

The sound with high frequency will be high pitch sound.

And the sound with low frequency will be low pitch sound.

(Option A)Frequency.

9)

If the pitch of the sound increases,the frequency of the sound will increases.

We have frequency of the sound inversely proportional to the time period of the sound.

So,here the time period of the wave decreases.

(option D)

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