Sound Waves and Resonance

Question 1

is there a net transfer of energy in an standing wave?

Answer 1

no, energy is trapped at the nodes

Question 2

what are points of no displacement on a wave called?

Answer 2

nodes aka no-deisplacement

Question 3

antinodes are points of…

Answer 3

maximum amplitude

Question 4

what is resonance?

Answer 4

resonance is when driving frequency = natural frequency

Question 5

what is harmonic frequency

Answer 5

harmonic frequencies are frequencies that can create beautiful observable standing waves

Question 6

for attached waves, what is the formula for length of string (2 nodes)

Answer 6

L = n * lambda/2 (number of half wavelengths)

Question 7

for open pipes, n nodes =?

Answer 7

n nodes = nth harmonic FOR OPEN PIPES

Question 8

OPEN PIPES ?????

Answer 8

L = n*lambda/2 !!! #NEVERFORGET`

Question 9

CLOSED PIPES???

Answer 9

L = n*lambda/4 BUT N CAN ONLY BE ODD

OR L = (2n-1)*lambda/2

Question 10

distinguish between transverse and longitudinal waves

Answer 10

in transverse waves, particles are vibrating perpendicular to the movement of the wave

however, in longitudinal waves, particles are moving parallel to the movement of the wave, causing compressions and rarefactions

Question 11

are sound waves transverse or longitudinal waves?

Answer 11

longitudinal

Question 12

how does speaking work

Answer 12

when you speak, you create compressions in longitudinal waves that increase amplitude in sound so that an audible sound can be heard.

Question 13

describe frequency and units

Answer 13

wavelengths per second (Hz)

Question 14

period = time it takes for one wavelength to pass thorugh a specified point

Answer 14

Period = time it takes for one wavelength to occur

Question 15

define the inverse square law

Answer 15

intensity will drop off proportionally with the square of the distance the wave has travelled

Question 16

describe the method of determining resonant frequency?

Answer 16

1. place an open glass tube into a container of water until almost fully submerged
2. strike and hold a tuning fork of a given frequency above open end of glass tube
3. raise tube until volume of sound reaches a peak (you have found resonant frequency)
4. use a rule to measure distance from water level to the open end of the glass tube

this distance must be the quarter wavelength,

therefore plug into v = flambda and v is the speed of sound