Course:PHYS341/2018/Assignments/A3

Part 1

For questions 1-2, fill in the gaps in each paragraph, choosing from the set of words/phrases at the end of each question (each of which may be used more than once) to form the most correct, precise statements. In the case where two words can be interchanged with no change in meaning, place them in alphabetical order (the code cannot handle more than one correct answer!).

1

A harmonic oscillator (e.g. a thin, taught string or a uniform narrow tube of air) resonates at a set of that are in integer ratios (e.g. 1:2:3:4... or 1:3:5:7...). The sound radiated by a oscillator consists of a set of partials, which are pure tones, and their are in the same integer ratios. If the of the partials are not in integer ratios the partials are said to . In all cases, musical of the sound is determined by the relative of the partials.

amplitudes, frequencies, harmonic, inharmonic, phases, speeds, timbre.

2

Sound sources that are much than the of the sound they are producing tend to radiate sound equally in all directions. Sound sources that are much than the of the sound they are producing tend to radiate sound only in particular directions. In a concert hall we can hear a cellist playing notes (whose is much than the size of the cello) only because sound is from and by all surfaces in the hall and will eventually reach our ears .

amplitude, absorbed, diffracted, frequency, high, low, smaller, larger, reflected, wavelength.

Part 2

For the following questions, select all statements that are correct; there may be more than one. When you have completed the quiz, I suggest to pay attention to all the comments, including those for wrong answers, even if you got it right first time.

1 A sound wave (pure tone) strikes a rigid wall in which there is a small circular aperture (diameter much smaller than the sound's wavelength):

	(a) It will not get through.
	(b) All the original wave will squeeze through the hole and proceed mostly in its original direction.
	(c) All the original wave will squeeze through the hole and spread out in all available directions.
	(d) The fraction of the original wave that strikes the hole will get through and proceed mostly in its original direction.
	(e) The fraction of the original wave that strikes the hole will get through and spread out in all available directions.

2 A sound wave (pure tone) strikes a rigid wall in which there is a large aperture (diameter much larger than the sound's wavelength):

	(a) It will not get through.
	(b) All the original wave will squeeze through the hole and proceed mostly in its original direction.
	(c) All the original wave will squeeze through the hole and spread out in all available directions.
	(d) The fraction of the original wave incident on the hole will get through and proceed mostly in its original direction.
	(e) The fraction of the original wave incident on the hole will get through and spread out in all available directions.

3 Two sound sources in a wide-open space play the same pure tone with equal amplitude; they are separated by about a wavelength (i.e. the separation is not small compared to the wavelength).

	(a) Walking around these sound sources you will sometimes hear the pure tone and sometimes hardly anything at all.
	(b) Walking around these sound sources you will always hear the tone at twice the volume of one of the sources alone.
	(c) Walking around these sound sources you will sometimes hear double the single pure tone's frequency and sometimes hardly anything at all.
	(d) Walking around these sound sources you will always hear double the single pure tone's frequency at the same volume.
	(e) Walking around these sound sources you will sometimes hear double the single pure tone's frequency and sometimes hardly anything at all.

4 The shape of the waveform (square, triangle, sawtooth etc.) of a sound wave affects -

	(a) the frequency.
	(b) the wavelength.
	(c) the amplitude.
	(d) the timbre.
	(e) the shape of the spectrum.