Chap 2 Level 1 And 2

Question 1

Define a wave in physics

Answer 1

A wave is a mechanism that transfers energy from one location to another

Question 2

What are the 2 types of wave s

Answer 2

Electromagnetic and mechanical waves

Question 3

Types of electromagnetic waves

Answer 3

Light
Heat
X-rays
Gamma rays
Tv signals

Question 4

What is an electromagnetic wave

Answer 4

A transfer of energy through a varying electrical & magnetic field

Question 5

What are mechanical waves

Answer 5

Require a physical interaction
Mechanical waves require a medium

Question 6

Examples of mechanical waves

Answer 6

Ocean waves
Sound waves
Guitar strings

Question 7

What are the two types of mechanical waves

Answer 7

Transverse and longitudinal

Question 8

What is a transverse wave

Answer 8

Particles move across or perpendicular to the wave propagation direction

Question 9

What are longitudinal waves

Answer 9

Particle motion moves across the direction of propagation
Dots represent particles
Particle closeness represents density

Question 10

How does sound travel in longitudinal waves

Answer 10

Sound travels through compresssions and rare fractions

Question 11

What are the 4 acoustic variables

Answer 11

Pressure
Density
Temperature
Particle motion

Question 12

What is pressure

Answer 12

A concentration of force/area
During compressipn, pressure increases
During rare fraction, pressure decreases

Question 13

Units of pressure

Answer 13

ATM
Mmhg
Pascals
Kg/m^2

Question 14

What is density

Answer 14

Density = mass/volume = kg/m^3

Question 15

What is temperature

Answer 15

Some wave energy is lost to heat in the medium due to vibrations
Temp fluctuates cyclically as concentrations move from high to low density

Question 16

Parameters of wave

Answer 16

Freq/period = determined by wave source
Wavelength = determined by wave source and prop of medium
Propagation velocity = determined by prop of medium
Amplitude = determined by wave source

Question 17

What is frequency and period

Answer 17

Period = how often an event occurs per time
Frequency = the # of compressions or rare fractions / time

Question 18

How to Determine frequency

Answer 18

Determined by source
If source creates many compressions per second, high freq. few compressions, low freq

Question 19

What is the period

Answer 19

The time that transpires between one compression to the next

Question 20

What is wavelength

Answer 20

The physical distance between
Compressions w/in a medium
Wavelength = propagation velocity/ frequency

Question 21

How to calculate amplitude

Answer 21

Max - mean / 2

Question 22

What is constructive interference

Answer 22

Occurs when 2 waves interact & produce one larger wave
Waves must be identical in frequency, wavelength, and amplitude

Question 23

What is destructive interference

Answer 23

When 2 waves are aligned that they’re max peak and min peak are the same
Completely cancels out amplitude

Question 24

Classification of sound and ranges

Answer 24

Infrasound: 0Hz - 20hz (below human audible)
Audible: 20hz-20khz (human audible)
Ultrasound: >20khz
Diagnostic: 2Mhz-20Mhz

Question 25

What is elasticity

Answer 25

The ability of a solid object to return its original shape after distortion by a force

Question 26

What is compressability

Answer 26

A measure of how much the volume of the material changes for a given force

Question 27

What is stiffness

Answer 27

Implies the inverse of elasticity of compressibility. A stiff material cannot be compressed

Question 28

What is bulk modulus

Answer 28

High bulk
Modulus: incompressible, inelastic, stiff
Low bulk modulus: compressible, elastic, not stiff

Question 29

Bulk modulus equation

Answer 29

C = bmodulus/density = stiffness/density

Question 30

Equation for intensity

Answer 30

Intensity = power/area
Power is proportional to (amplitude)^2

Question 31

What is the amplitude equation

Answer 31

20 x log(Af/Ai)