Sound and Color Flashcards
propagation:
The movement of the waves
the denser the rope, the (slower/faster) the speed of the propagation
slower
the higher the tension, the (higher/lower) the speed of the propagation on the string
higher
is light an electromagnetic wave?
yes
What is periodic motion? (T)
the time it takes for a motion to repeat (unit=secs)
frequency (f)
the rate at which the motion repeats (units= 1/sec, or Hz)
wavelength
the distance wave travels during one period
what are the 3 characteristics of color?
hue: what the color is
saturation: how ‘pure’ the color is. The less white, the more saturated, color purity
brightness: how dark or light the color is
Additive color mixing
the mixing of light, almost all colors can be produced through mixing 3 primary colors (R, G, B)
when R, G, and B are mixed in equal amounts, they produce what color?
white
what are the complementary colors of R, G, and B?
R - cyan
G - Magenta
B - yellow
How do you make white with complementary colors?
two colors, when added in equal amounts, equal white.
ex. Red + cyan =white
what do variables r, g, b stand for? What is their sum?
these are fractions of R, G, B. They add up to 1
What are secondary colors?
equal mixtures of 2 primary colors
Color triangle rule:
when you add 2 colors, the resulting color always lies on the line joining the colors
ex. yellow = 1/2g +1/2r
cyan = 0r +1/2g
Where is additive color mixing used in?
projectors, music displays, television
what is the r, g, b for white?
all are 1/3
where is gray on the color triangle?
the same place as white
which element does the color triangle not indicate?
intensity
What are the low intensities of orange, white, and green?
orange–brown
white–gray
green–olive
What are the wavelengths for blue, green, and red?
blue: 400-500
green: 500-600
red: 600-700
what does red reflect and absorb? green? blue?
red absorbs green and blue, it reflects red
green absorbs red and blue, reflects green
blue absorbs red and green, it reflects blue
what is transmittance?
the fraction of light incident on the filter that passes through
formula for net transmittance?
T =Ta x Tb
what are the subtractive primaries?
C + M =?
M + Y =?
Y + C=?
subtractive primaries: cyan, yellow, and magenta
1. B
2. R
3. G
what is the reflectance eqn? What do you use it for?
R = Ra x Rb; you use it for pigments (paints)
what is low lightness orange?
brown
When two orange filters are put together, what color do they make?
reddish-orange
optional:
sky blue + orange = ?
purple + purple = ?
- sat. orange (brown)
- blue
where does light come from? What is the Quantum nature of matter?
atoms and molecules can absorb or emit light with discrete wavelengths
what is a spectrum?
an atomic ‘fingerprint’ used to identify atoms
describe light emission from atoms:
atoms emit radiation at certain frequencies
emission patterns are unique to atoms
What is periodic motion? What is an example?
motion that repeats in time; a swing
What is fundamental property?
how long it takes for a motion to repeat, the period of the motion
Period (T)
time it take for a motion to repeat
Frequency (f)
the rate at which the motion repeats
Simple harmonic motion
the periodic motion described by a sine function
what is frequency in music?
the pitch you hear (what note)
What is amplitude in music:
a measure of intensity of sound.
What is the formula for volume?
(amplitude)^2
What is Hooke’s Law? Define the variables
the amount of force exerted by a spring
F = k x X
k= spring constant
X = amount spring is stretched or compressed
Oscillation frequency for spring, define the variables.
f = 1/2(pi) x sqrt(k/m)
k = spring constant
m = mass
increasing the spring constant ____ the oscillation freq,
decreasing the spring constant ____ the oscillation freq,
increases; decreases
does the oscillation frequency of a simple harmonic oscillator depend on amplitude?
no
formula for the frequency of a tuning fork:
f = 1/ sqrt(m)
m= mass
what happens when you increase the mass of a tuning fork?
the pitch lowers
the propagation speed:
the disturbance moves at a well defined speed
wave:
traveling shape in a medium
describe sound waves
the are pressure waves formed from a series of compressions and rarefactions
compressions: high air pressure
rarefactions: low air pressure, changes in air pressure
speed formula
speed = d/t
d = distance
t= time
longitudinal waves:
- direction of disturbance same as direction of propagation
- compression and rarefaction waves
- like a slinky
- sound waves
transverse waves:
- direction of disturbance is perpendicular to propagation
- do not require medium for propagation
what is the speed of light in a vacuum?
What is the speed of sound at 21C in dry air?
3 x 10^8 m/s
344.0 m/s
How do you find the speed of sound when it is not 21C?
v = (344 + 0.6 x T)
T = temperature in C
What is a standing wave?
the sum of two waves of the same frequency that move in opposite directions
What is a node?
places where the string/wave never moves
What is an antinode?
halfway between nodes, where amplitude of wave is at a maximum
Do the locations of the nodes and antinodes change in time?
no
wave speed (v) formula:
v = (wavelength)(t)
t = time
period (T) formula:
T = 1/f
The higher the mode, the _______ the number of nodes
greater
what is the frequency of a standing wave?
f = v/wavelength
What is the frequency of f1, f2, f3
f1 = v/(2L)
f2= v/L
f3 = 3/(2L)
wave velocity on a string (v) formula:
v = sqrt(F/p)
F = tension on string
p = mas per unit
Fundamental frequency of a string (f):
f = v/(2L) x sqrt(F/p)
What happens when you double the tension on the fundamental frequency of a string?
it increases by sqrt(2) = 1.41
f = v/(2L) x sqrt(2F/p)
Mode with the lowest frequency is called the _____ mode
Modes with higher frequencies are called_______
- fundamental
- Overtones (aka harmonics)
What is the eqn for the harmonic series?
fn = nf1 n=1,2,3…
frequency is proportional to
1/L
formula for F (tension)
F = kg x 9.8
answer in N (newtons)
What is formula for p (mass per unit length)
p = M/L
What is the relationship between frequency and tension?
frequency = sqrt(tension)
f = sqrt(F)
