### PHYS207    Spring2013 Set 1  assignment:

#### Concepts you may be asked to explain briefly:

reflection / refraction / absorption
interference / superposition
diffraction / Huygens' Principle
oscillator: simple / damped / driven
modes and nodes, including the derivation of fn = n f1
standing waves and resonance
waveform / wavefront / wavelength / period / frequency / speed of propagation
amplitude / phase / spectrum
mechanism of hearing: (eardrum, Eustachian tube, cochlea, basilar membrane, hair cells)
loudness vs. intensity: critical band, Sound Intensity, Sound Intensity Level, Loudness level, Loudness

Text:
Chapter 1 RQ 3,6,7,10,12,16 E 4,5,9,11
Chapter 2 RQ 2,4,5,6,7 Q 1,4 E 1,2,4
Chapter 3 RQ 1,3,4,5,12,13,14,15 Q 4 E2,3,4,5,6,7
Chapter 4 RQ 4,8 Q 4 E 3,5,6
Chapter 5 RQ 1,2,3,9,10 Ex. 1,2,3,6
Chapter 6 RQ 5,10 Q Ex. 1,2,3,5

Problem A: Construct a log scale with ticks at 1,2,3,4,5,6,7,8,9,10,20,30,40,50,60,70,80,90,100
using a blank piece of paper, pencil, and log 2 = 0.3

Problem B: Draw on
a) lin-lin scale
b) log(vertical)-lin(horiz)  scale
for x in the range from -6 to +6, the graphs of the functions:

y1(x) = 10^-x
y2(x) = 1+10^-x
y3(x) = 2+10^-x
y4(x) = 1+sin(pi x) +10^-x

For the log scale, ticks at powers of ten will suffice, i.e. don't bother

Problem C: Use your calculator to determine log 850 and log 1150.
Check your results against log 1000.

```Problem E: You are listening to your favored music at the threshold of pain
(110 phons) at 50 Hz as well as at 1 kHz and at 6 kHz. When neighbours
complain, you reduce the sound intensity level by a factor of million
(independent of frequency). Determine the resulting loudness (sones)
at the three frequencies, and compare with the original.

Problem F: Two incoherent sources (e.g. violinists) emit sound of same power,
at frequencies f1 and f2, respectively. What can you say about the
resulting sound as compared to the two separate sounds, if
a) f1 = 1000 Hz f2 = 1000 Hz
b) f1 = 1000 Hz f2 = 1500 Hz
c) f1 =  150 Hz f2 = 3500 Hz

Problem G: If one violin produces SIL of 75 dB
a) what will you get from two violins (playing unison)
b) how much from 10 violins?
c) how many violins do you need to get to 95 dB?```
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`Plus: the problems labeled HW in the Math and Physics handout`
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