Waves
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Waves as PDF for free.
More details
- Words: 681
- Pages: 7
GIKPKC7 94107
Waves I
Page 1
Introduction 28/7/98
Terms: Wavelength () Period (T) Amplitude (A) Frequency (f or n) Wave number (k) Velocity ( v )
Distance between two points which are in phase (m) Time taken for one wavelength to complete one cycle (s) The maximum displacement of a particle from the equilibrium position (m) Number of complete wavelengths in 1 second (Hz) Number of waves in 1 metre (m-1) Velocity though the medium (m.s-1)
Waves enable the transfer of energy from one place to another. The two main types of waves are mechanical waves & electromagnetic waves.
Electromagnetic Waves:
An electromagnetic wave is a series of magnetic and electric fields naturally at right angles. Caused by particles moving.
Mechanical Waves:
These waves involve the transmission of energy through some sort of medium. The medium is temporarily distorted as the wave propagates. One single distortion or disturbance in the medium is called a pulse. A series of pulses comprises a continuous wave.
Types of Mechanical Waves: Transverse
A number of transverse pulses results in a transverse wave. Propagation (motion) is perpendicular to disturbance. They do not transmit through the bulk of a liquid since the transverse distortion in a liquid is independent of the next successive section of the medium. They can only travel over the surface of liquids where surface tension and gravity act to restore the medium and promote the movement of the transverse distortion to the next part of the surface. A Transverse Pulse
Transverse Wave Direction of Energy Transfer
Direction of Energy Transfer
Vibration
Transverse Distortion
Luke Cole
Page 1
GIKPKC7 94107
Waves I
Page 2
Longitudinal
A number of longitudinal pulses results in a longitudinal wave The distortion of the medium is parallel to the direction of energy transfer. Sections close together are called compressions. Sections farthest apart are called rarefactions. Common compression wave such as ‘sound’ can travel through the bulk of water. Sound cannot travel through a vacuum (unlike electromagnetic radiation) so there can be no sound heard in space. Longitudinal Pulse
Longitudinal (Compression) Wave
Direction of Energy Transfer
Compression
Distortion
Rarefaction
Torsional
A torsional pulses results from a rotational (or twisting) distortion, which is propagated along a solid. A number of torsional pulses results in a torsional wave Torsional Pulse Energy Transfer Rotational Distortion
Luke Cole
Page 2
GIKPKC7 94107
Waves I
Page 3
Wave Characteristics 31/7/98
Amplitude
Wavelength
1 T f = Frequency (Hz) T = Period (s)
Equation:
f=
Equation:
k=
Equation:
1 k = Wave number (m-1) = Wavelength (m) v = .f v = Velocity (m.s-1) = Wavelength (m) f = Frequency (Hz)
Luke Cole
Page 3
GIKPKC7 94107
Waves I
Page 4
Superposition
The resultant wave can be determined by adding the amplitudes of the individual waves at a number of key points.
Luke Cole
Page 4
GIKPKC7 94107
Waves I
Page 5
A
D
+
B
C
E
=
A+B
C D+E
Wave Changes 5/8/98
Wave Reflecting at a Boundary: Luke Cole
Page 5
GIKPKC7 94107
Waves I
Page 6
Fixed to the Wall
Free to Move Motion
Motion s = String
F = m s .a s
FU =p ms .a s Newton 3rd Law
FD
o= w mnw .aw
w = Wall
However, mUp < mDown Since, free to move, no change in phase the string suffers a phase change of rad Motion
Motion
Equation:
FT v = Velocity of a pulse (m.s-1) F T = Tension (N) = Mass per unit length (kg.m-1)
v=
A Change of Medium:
Part of the pulse will be deflected and part will be transmitted.
Luke Cole
Page 6
GIKPKC7 94107
Waves I
Light to Heavy String
Page 7
Heavy to Light String
Motion
Motion
Motion
Motion
Motion
Motion
Pulse travels slow in the heavy string
Pulse travels more quickly in the light string
Luke Cole
Page 7
Waves I
Page 1
Introduction 28/7/98
Terms: Wavelength () Period (T) Amplitude (A) Frequency (f or n) Wave number (k) Velocity ( v )
Distance between two points which are in phase (m) Time taken for one wavelength to complete one cycle (s) The maximum displacement of a particle from the equilibrium position (m) Number of complete wavelengths in 1 second (Hz) Number of waves in 1 metre (m-1) Velocity though the medium (m.s-1)
Waves enable the transfer of energy from one place to another. The two main types of waves are mechanical waves & electromagnetic waves.
Electromagnetic Waves:
An electromagnetic wave is a series of magnetic and electric fields naturally at right angles. Caused by particles moving.
Mechanical Waves:
These waves involve the transmission of energy through some sort of medium. The medium is temporarily distorted as the wave propagates. One single distortion or disturbance in the medium is called a pulse. A series of pulses comprises a continuous wave.
Types of Mechanical Waves: Transverse
A number of transverse pulses results in a transverse wave. Propagation (motion) is perpendicular to disturbance. They do not transmit through the bulk of a liquid since the transverse distortion in a liquid is independent of the next successive section of the medium. They can only travel over the surface of liquids where surface tension and gravity act to restore the medium and promote the movement of the transverse distortion to the next part of the surface. A Transverse Pulse
Transverse Wave Direction of Energy Transfer
Direction of Energy Transfer
Vibration
Transverse Distortion
Luke Cole
Page 1
GIKPKC7 94107
Waves I
Page 2
Longitudinal
A number of longitudinal pulses results in a longitudinal wave The distortion of the medium is parallel to the direction of energy transfer. Sections close together are called compressions. Sections farthest apart are called rarefactions. Common compression wave such as ‘sound’ can travel through the bulk of water. Sound cannot travel through a vacuum (unlike electromagnetic radiation) so there can be no sound heard in space. Longitudinal Pulse
Longitudinal (Compression) Wave
Direction of Energy Transfer
Compression
Distortion
Rarefaction
Torsional
A torsional pulses results from a rotational (or twisting) distortion, which is propagated along a solid. A number of torsional pulses results in a torsional wave Torsional Pulse Energy Transfer Rotational Distortion
Luke Cole
Page 2
GIKPKC7 94107
Waves I
Page 3
Wave Characteristics 31/7/98
Amplitude
Wavelength
1 T f = Frequency (Hz) T = Period (s)
Equation:
f=
Equation:
k=
Equation:
1 k = Wave number (m-1) = Wavelength (m) v = .f v = Velocity (m.s-1) = Wavelength (m) f = Frequency (Hz)
Luke Cole
Page 3
GIKPKC7 94107
Waves I
Page 4
Superposition
The resultant wave can be determined by adding the amplitudes of the individual waves at a number of key points.
Luke Cole
Page 4
GIKPKC7 94107
Waves I
Page 5
A
D
+
B
C
E
=
A+B
C D+E
Wave Changes 5/8/98
Wave Reflecting at a Boundary: Luke Cole
Page 5
GIKPKC7 94107
Waves I
Page 6
Fixed to the Wall
Free to Move Motion
Motion s = String
F = m s .a s
FU =p ms .a s Newton 3rd Law
FD
o= w mnw .aw
w = Wall
However, mUp < mDown Since, free to move, no change in phase the string suffers a phase change of rad Motion
Motion
Equation:
FT v = Velocity of a pulse (m.s-1) F T = Tension (N) = Mass per unit length (kg.m-1)
v=
A Change of Medium:
Part of the pulse will be deflected and part will be transmitted.
Luke Cole
Page 6
GIKPKC7 94107
Waves I
Light to Heavy String
Page 7
Heavy to Light String
Motion
Motion
Motion
Motion
Motion
Motion
Pulse travels slow in the heavy string
Pulse travels more quickly in the light string
Luke Cole
Page 7
