waves part 1 basics what is a wave? a wave is a disturbance that carries energy through matter or...

39
Waves Part 1 Basics

Upload: bryan-stephens

Post on 18-Jan-2016

234 views

Category:

Documents


5 download

TRANSCRIPT

Page 1: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

WavesPart 1

Basics

Page 2: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

What is a wave?

•A wave is a disturbance that carries energy through matter or space

Page 3: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves Themes

These are some of the areas of interest that involve waves

1. Sight and vision2. Sound and hearing3. Communications4. Medicine5. Cooking6. astronomyAnd more…………

Page 4: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

The uses of waves

1. Microwave

2. Radar

3. Mobile

4. TV

5. Radio

6. CD

7. Music

8. Satellite

1. X-rays

2. Ultrasound

3. Gamma-rays

4. Fibre optics

5. Remote control

6. …..

7. …..

Page 5: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

The characteristics of waves

Waves are

1. Regular patterns of disturbance

2. Made by vibrations

They

3. Transmit energy

4. Do not transmit matter

Page 6: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

The two main types

Transverse (b)1. on a rope 2. on the surface of

water3. light

Longitudinal (a)

1. in a spring

2. Sound

longitudinal

transverse

Page 7: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

• When a crowd does “the Mexican wave” at a sporting event, they are performing as a transverse wave

• The wave moves in a circle around the stadium, but the people move up and down

Transverse WavesWaves

Transverse particle motion

Page 8: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Transverse particle motion

The motion of the particles in the medium is at a right angle to the motion of the

wave as a whole

Page 9: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Transverse particle motion

Page 10: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Longitudinal

The particles move in the same direction as the wave motion

Page 11: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Terms – wavelength - longitudinal

Compression (C) – rarefaction (R)

λC R C R C R

=wavelength

Page 12: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Terms – wavelength - transverse

Crest (C) –Trough (T)

T T

C C Cλ =wavelength

Page 13: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Terms – wavelength

Wavelength The distance between two consecutive

• Crests or troughs• Compressions or rarefactions

Page 14: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Terms – amplitude - longitudinal

Amplitude

The maximum (biggest) disturbance or displacement.

Page 15: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Terms - frequency

Frequency

The number of waves made or passing by in 1 second

Unit – Hertz (Hz)

Page 16: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Terms - speed

Speed

The distance a wave travels in one second.

start 1 second later

Page 17: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Symbols and units

unit symbol

amplitude m A

wavelength m λ or w

frequency Hz f

speed m/s s,v or c!

Page 18: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Formula

s,v or c -speed

w or λ – wavelength

s

f λ

Page 19: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves on water

Page 20: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Transverse waves on water – a side view

Direction of travel

Particle motion – not 100% correct!

Page 21: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Transverse waves on water – from above

= wave motion

= crest

= source

Waves travelling out from the source

Page 22: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves spreading

The previous slides show waves moving

along a line.

Waves can spread out moving

• across the surface of the sea ( 2 dimensions)

• or through space ( 3 dimensions)

Page 23: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Light and sound

Light

1. Transmits energy

2. Transverse

3. Does not need a medium – can travel through empty space

Sound

1. Transmits energy

2. Longitudinal

3. Needs a medium – solid – liquid - gas

Page 24: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Wave Interactions--Reflection

•Reflection is what happens when a wave strikes a surface or boundary

• Waves reflect at a free boundary

• At a fixed boundary, waves reflect and turn upside down

Page 25: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Reflection -sound

1. Sound is reflected when it meets a boundary between two materials – air/brick.

2. Reflected sound can produce an echo.

Page 26: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Echo - reflection

Page 27: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Reflection – spring waves

Waves can be reflected at the fixed end of a spring.

Page 28: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Reflection - light

1. Light is reflected when it meets a boundary between two materials – air/mirror – air/paper.

2. Light reflected by a mirror produces an image.

Page 29: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Reflection – light - diagrams

Reflection by a plane mirror

Page 30: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Reflection – water waves - diagrams

Water waves are reflected by barriers

Page 31: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Refraction - light

• When waves pass from one medium into another, they are bending due to a process called refraction

• This is why a spoon looks like it is broken into 2 pieces when it is resting in a glass half-full of water

Page 32: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Refraction – light - diagrams

There is some reflection as well.

Page 33: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Refraction- water waves – diagrams -1

When water waves pass from deep water to shallow water they slow down. The wavelength decreases .

deep-fast shallow-slow

Page 34: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Refraction- water waves – diagrams -2

deep shallow

The direction changes as well – this is refraction

Page 35: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Diffraction

Waves spread when they

1. pass through a gap

2. go past an obstacle

Page 36: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Diffraction – narrow slit

Narrow slit – more diffraction

Page 37: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Diffraction – wide slit

Wide slit – less diffraction

Page 38: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Diffraction – past an obstacle -1

Short radio waves – less diffraction

Radio

transmitter

No reception

Page 39: Waves Part 1 Basics What is a wave? A wave is a disturbance that carries energy through matter or space

Waves

Diffraction – past an obstacle -2

Long radio waves – more diffraction

Radio

transmitter

reception