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Transcript of Oscillation+and+waves
OSCILLATION AND WAVES
THE NATURE OF A WAVE
We encounter waves daily, such as sound waves, visible light waves, radio waves, microwaves, water waves, flag waves & stadium waves.
WAVE
Wave – a rhythmic disturbance that transfers energy through matter or space
Carries energy without transporting matter from place to place
Wave
Mechanical Waves
Transverse
Longitudinal
Electromagnetic Waves
Main types of Wave
1. Mechanical Waves act as the propagation of a disturbance through a material medium due to the repeated periodic motion of the particles of the medium about their mean positions, the disturbance being handed over from one particle to the next.
2. Electromagnetic Waves are the disturbance, which does not require any material medium for its propagation and can travel even through vacuum. They are caused due to varying electric and magnetic fields.
Wave
Mechanical Waves
Transverse
Longitudinal
Electromagnetic Waves
Mechanical Waves
Mechanical Waves act as the propagation of a disturbance through a material medium due to the repeated periodic motion of the particles of the medium about their mean positions, the disturbance being handed over from one particle to the next.
A medium is a substance or material that carries the waveMechanical waves are of two types:
1. Transverse Wave2. Longitudinal Wave.
Wave
Mechanical Waves
Transverse
Longitudinal
Electromagnetic Waves
Types of Mechanical Waves:Transverse
Compressional/ Longitudinal
Transverse waves – matter moves in the medium back and forth at right angles to the direction that the wave is travelingLight waves & water waves
Compressional waves – matter in the medium moves back and forth in the same direction that the wave travelsSound waves
TRANSVERSE WAVE
The crest of a wave is the point on the medium that exhibits the maximum amount of positive or upward displacement from the rest position. Points C and J on the diagram represent the troughs of this wave.
The trough of a wave is the point on the medium that exhibits the maximum amount of negative or downwar
The amplitude of a wave refers to the maximum amount of displacement of a particle on the medium from its rest position. In a sense, the amplitude is the distance from rest to crest. d displacement from the rest position.
The wavelength of a wave is simply the length of one complete wave cycle.
LONGITUDINAL WAVE
A compression is a point on a medium through which a longitudinal wave is traveling that has the maximum density. A region where the coils are spread apart, thus maximizing the distance between coils, is known as a rarefaction.
A rarefaction is a point on a medium through which a longitudinal wave is traveling that has the minimum density.
Points A, C and E on the diagram above represent compressions and points B, D, and F represent rarefactions.
FREQUENCY AND PERIOD
Frequency – the number of waves that pass a given point each secondMeasured in Hertz = 1/sec Period: The amount of time it takes
one wavelength to pass a point
PERIOD AND FREQUENCY RELATIONSHIP
T = periodf = frequency
Period FrequencyT= 1/f f = 1/T
One hertz is equal to one peak (or cycle) per second. 1/sec
SAMPLE PROBLEM
What is the period of a spring that is oscillating in a frequency of 27.1Hz.?
T=1/fT=1/27.1Hz
T=0.04/s
SPEED OF WAVES
v=λf
Where v=speedλ=wavelengthf=frequency
Sample problem:Radio waves travel at 3.0x108 m/s.
If an FM station operates with a frequency of 96.3MHz, how long is one complete wave?
SAMPLE PROBLEM:
Radio waves travel at 3.0x108 m/s. If an FM station operates with a frequency of 96.3MHz, how long is one complete wave?
Given: v= 3.0x108 m/s. f= 96.3MHz or 96.3x106 HzFind: λFormula to use: v=λf
λ=v/fλ= 3.0x108 m/s. / 96.3x106 Hz
λ=3.12m
RarefactionsCompressionsTroughsCrests
General Wave Properties
Types of WavesWave Terms
Transverse LongitudinalFrequency
Period
Speed
Amplitude
Wavelength
Frequency
Periodf = 1/T
Speed, v = fl
RECTILINEAR MOTION. Waves travel in a straight line through a uniform medium.
RECTILINEAR MOTION
PROPERTIES OF WAVES
PROPERTIES OF WAVES1. REFLECTION. The bouncing off of waves when encountering an obstruction.
θi
θr
Reflected waves
Normal
Incident waves
BARRIER
PROPERTIES OF WAVES
2. REFRACTION. The bending of waves when passing from one medium of different density to another. N
O
N’
R’
I
θi
θr
High density medium
Low density medium
PROPERTIES OF WAVES
REFRACTION.
2
ongol
M
One good example is the bending of pencil in a glass of water. The pencil seemed to be bent when viewed from the side.
This is because the speed of light in air is faster than its speed in water. The light reflected by the pencil in air reached our eyes first before the light reflected by the pencil in water. Our brain perceives it as bent because of the difference in the time it reached it.
PROPERTIES OF WAVES
3. INTERFERENCE.
The meeting of two waves at a point is called interference.
INTERFERENCEw2
w1
w2w1
W1+ W2
1.
2.
3
INTERFERENCE
w1
w1w2
4.
5. w2
PROPERTIES OF WAVES
4. DIFFRACTION.
The spreading of waves as they enter the opening of a barrier.
PROPERTIES OF WAVES
DIFFRACTION.
WAVE FRONTS
DIFFRACTED WAVES
BARRIERS
OPENING
RarefactionsCompressions
TroughsCrests
General Wave Properties
Types of Waves
Wave Terms
Transverse
Longitudinal
Speed
Amplitude
Wavelength
Frequency
Periodf = 1/T
Speed, v = fl
Properties of Waves
Rectilinear Motion
Reflection
Refraction
Interference
Diffraction
Mechanical Waves
Electromagnetic Waves