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