Waves Flashcards

1
Q

Wave Motion

A

Kind of disturbance which travels through a medium due to repeated vibrations of the particles of the medium about their mean positions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Propagation of Sound Waves through Air

A
  • A small region in air is likes a spring - As it travell through the air, it compresses or expands it
  • If a region is compressed, density increases of the second region causeing the first region density to decrease
  • This causes rarefaction and hence shifts it to adjacent region
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Propagation of sound in a solid

A
  • When an eleastic wave propagates, the atom is displaced from its equilibrium position and a restoring force is developed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Transverse Waves

A
  • Waves in which the individual particles of the medium oscillate perpendicular to the direction of wave propagation
  • Travel through a liquid medium
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Longitudinal Waves

A
  • Waves in which the individual particles of the medium oscillate along the direction of wave propagation
  • Travel through all media
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Angular Frequency

A

Rate of change of phase with time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Wavelength

A

Distance covered by a wave during the time in which a particle of the medium completes one vibration to and fro about its mean position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Angular wave number / Propagation constant

A

Quantity 2pi / lambda (phase change per unit path difference)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Wave velocity / Phase velocity

A

Direction covered by a wave per unit time in its direction of propagation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Speed of transverse wave on stretched string

A

v = root (T / m)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Speed of a transverse wave in a solid

A

v = root (modulus of rigidity (aka shear modulus) / ro)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Speed of longitudinal Wave in a liquid or gas

A

v = root (k / ro)
k = bulk modulus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Speed of longitudinal wave in a solid

A

root (k + 4/3 * shear modulus) / ro)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Speed of a longitudinal wave in a solid rod

A

v = root (Y / ro)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Newton’s Formula for speed of sound in a gas

A

v = root (P / ro)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Laplace formula for speed of sound in a gas

A

v = root (gamma * P / ro)
gamma = Cp / Cv

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Plane Progressive harmonic wave

A

If during the propagation of a wave through a medium, the particles of the medium vibrate simple harmonically about their mean positions, then the wave is said to be plane progressive

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Factors which affect speed of sound in a gas

A
  • Pressure has no effect!
  • At constant pressure, v inversely proportional to square root of density
  • Travels faster in moist air than dry hair
  • Directly proportional to square root of abs. temp
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Progressive Wave

A

Wave that travels from one point of the medium to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Angular wave number or Propagation constant

A

k = 2pi / lambda

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

y(x,t) =

A

A sin (omega t - kx)
= A sin 2 pi(t / T - x / lambda)
= A sin 2pi/T (t - x / v) = A sin 2pi / lambda (vt - x)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Explain Progressive wave

A

y = A sin (omega t - kx + psi not)
y = Displacement
A = amplitude
omega = angular freq
t = time
k = angular wave number
x = position
psi not = initial phase angle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Phase of a wave

A

Quantity that gives complete information of the wave at any time and at any position

24
Q
A
25
Q

Time period of a wave

A

Time in which the phase of a particle of the medium changes by 2pi

26
Q

Wavelength

A

Distance between two points which have a phase difference of 2pi at any given instant

27
Q

Particle velocity

A

Velocity with which the particles of the medium vibrate about their mean positions

28
Q

Wave velocity

A

Distance covered by a wave in the direction of its propagation per unit time

29
Q

Acceleration amplitude / maximum value of acceleration

A

a = (2pi / T)^2

30
Q

Particle Acceleration

A

acceleration (rate of change in speed and direction) of particles

31
Q

Displacement along negative x-axis

A

y = A sin (omega t + kx)

32
Q

phase formula

A

2pi (t / T - x / lambda) + psi not

33
Q

Reflection of a wave from a rigid body

A

It is reflected back with a phase reversal or phase difference of pi radians

34
Q

Reflection of a wave from an open boundary

A

Suffers no phase change

35
Q

Node

A

A node is a point along a standing wave where the wave has minimum amplitude

36
Q

Antinode

A

An antinode wave is a point on a standing wave where the amplitude of the wave is at its maximum

37
Q

Waves during refraction from one medium to another

A

Suffers no phase change

38
Q

Principle of superposition of waves

A

When a number of waves travel through a medium simultaneously, the resultant displacement of any particle of the medium at any given time is equal to the algebraic sum of the displacements due to individual waves

39
Q

Constructive interference

A

When two waves travel in the same direction and are in phase with each other, their amplitude gets added, and the resultant wave is obtained.

40
Q

Destructive interference

A
  • Destructive interference occurs when waves come together so that they completely cancel each other out.
  • Same amplitude in opposite directions
41
Q

Stationary waves

A

When two identical waves of same amplitude and frequncy travelling in opposite directions with the same speed along the same path superpose each other, the resultant wave does not travel in the either direction

42
Q

Equation of stationary wave

A

y = (2A cos kx) sin omega t

43
Q

Characteristics of stationary waves

A
  1. Disturbance does not advance forward
  2. All particules, except at nodes, execute SHM
  3. Nodes and antinodes
  4. Distance between two successive nodes is lambda / 2
  5. Amplitudes different at different points
  6. Has same wavelength and time period as two component waves
44
Q

Comparison between stationary and progressive waves

A

-

45
Q

First harmonic / Fundamental frequency

A

The first harmonic, also known as the fundamental frequency, is the lowest frequency at which a string or air column can vibrate to create a standing wave pattern

46
Q

Normal Modes

A

A normal mode of a dynamical system is a pattern of motion in which all parts of the system move sinusoidally with the same frequency and with a fixed phase relation

47
Q

Sinusoidally

A

Sinusoidally means relating to, shaped like, or varying according to a sine curve or sine wave

48
Q

Velocity when it vibrates in p segments

A

Vp = p / 2L (root (T / m))

49
Q

A pipe of length L with one end closed and other end open vibrates with frequencies given by

A

v = (n + 1/2) mu / 2L
Fundamental mode / First harmonic is v = mu / 4L

50
Q

Beats

A

Periodic variations in the intensity of sound caused by the superposition of two sound waves of slightly different frequencies

51
Q

Beat frequency

A

Difference in frequencies of two superposing waves (v1 - v2)

52
Q

A
53
Q
A
54
Q
A
55
Q
A