### PHYS207 Spring2014 HW Set 1
assignment; covers skills for EXAM 1

#### 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 f_{n} = n f_{1 }

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

addition of sounds, masking

**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

**Additional problems:**

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

subdividing the decades.

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