UNIT 3: WAVES

S8P4

PRE-TEST OVER WAVES (S8P4)

VOCABULARY

• Wave –

• Medium –

• Mechanical waves -

• Vibration –

• Transverse wave –

• Crest –

• Trough –

• Longitudinal waves –

• Compressions –

• Rarefactions –

• ELECTROMAGNETIC WAVE –

• The ELECTROMAGNETIC SPECTRUM –

• RADIO WAVES –

• MICROWAVES –

• VISIBLE LIGHT –

• INFRARED RAYS –

• ULTRAVIOLET RAYS –

• X-RAYS –

• GAMMA RAYS –

VOCABULARY

• Wave - A disturbance that transfers

energy from place to place.

• Medium - The material through which

a wave travels

• Mechanical waves - waves that need a

medium to travel through.

• Vibration - a repeated back-and-forth

or up-and-down motion

• Transverse wave - the matter in the

wave moves up and down (across) at a

right angle to the direction of the

wave

•

• Compressions - parts where the coils are close together

• Rarefactions - parts where the coils are spread out

• ELECTROMAGNETIC WAVE - a transverse wave that

transfers electrical and magnetic energy.

• The ELECTROMAGNETIC SPECTRUM - the complete range of

electromagnetic waves placed in order of increasing

frequency.

• RADIO WAVES - have the longest wavelengths and lowest

frequency

• MICROWAVES – Radio waves with the shortest wavelengths

and highest frequencies

• INFRARED RAYS - electromagnetic waves with wavelengths

shorter than those of radio waves.

• ULTRAVIOLET RAYS - electromagnetic waves with wavelengths

that are just shorter than those of visible light

• X-RAYS - electromagnetic waves whose wavelengths are just

shorter than those of ultraviolet rays.

• GAMMA RAYS - electromagnetic waves with the shortest

wavelengths and highest frequencies

THE BIG IDEA

•S8P4. Students will explore the wave nature of sound

and electromagnetic radiation.

•Explore - travel in or through (an unfamiliar

country or area) in order to learn about or

familiarize oneself with it.

CURTIS – PHYSICAL SCIENCE

S8P2

S8P4A: IDENTIFY THE CHARACTERISTICS OF MECHANICAL WAVES.

• Identify - establish or indicate who or what

(someone or something) is.

WHAT TYPES OF WAVES DO YOU SEE?

WHAT IS A WAVE?•A disturbance that transfers energy from place to place. •Energy is the ability to do work

•You are sitting on a raft in the middle of the ocean. A big boat goes by creating a wave in the water. •What work will that wave do to your raft?

WHAT CARRIES WAVES?•Most waves need something to travel through.

•The material through which a wave travels is called a

medium.

What is an ocean wave’smedium?

What is the medium for the sound waves

that come from a musical instrument?

SO WAVES CAN TRAVEL THROUGH LIQUIDS AND GASES…

•What about solids?

•Can you think of any examples?

MECHANICAL WAVES

•Mechanical waves are waves that need a medium to travel through.•Mediums can be solid, liquid, or gas.

Can you remember what kind of wave carries energy

through empty space?

HINT: RadiationELECTROMAGNETIC

HOW DO WAVES TRANSFER ENERGY?

•Although mechanical waves travel through a

medium, they do not carry the medium with them.

HOW DO WE KNOW WAVES CARRY ENERGY AND NOT MATTER?• Think about an earthquake.•When seismic waves travel through

an area, the ground shakes from side to side and up and down, but the ground itself does not travel over a distance.•Only the ENERGY moves!

ANOTHER EXAMPLE…

• Waves travel through the water but they do not carry

the water or the bottle with them.

WHY DOESN’T THE MEDIUM TRAVEL ALONG WITH THE WAVE?

• All mediums are made up of tiny particles.

• When a wave enters a medium, it transfers energy to the medium’s particles.

• Then the particles bump into each other, passing the wave’s energy along.

IT’S LIKE PASSING FOOD AT THE DINNER TABLE!

WHAT CAUSES WAVES?

•You MUST have energy.

•Mechanical waves are produced when a

source of energy causes a medium to vibrate.

•A vibration is a repeated back-and-forth or up-

and-down motion.

•When a vibration moves through a medium, a

wave results.

EXAMPLES

TYPES OF WAVES

•Mechanical waves are classified by

•The way they move the medium through which they

travel

•There are two types of waves

•Transverse waves

•Longitudinal waves

TRANSVERSE WAVES

Transverse means “across”

In a transverse wave the matter in the wave moves up and

down (across) at a right angle to the direction of the waveDirection of Wave

Direction of Medium

TRANSVERSE WAVES CREATE POINTS CALLED “CRESTS” AND “TROUGHS”, OR HIGH AND LOW POINTS IN THE WAVES MOVEMENT.

LONGITUDINAL WAVES•Longitudinal waves move the medium parallel to the

direction in which the wave travels.

Direction of Wave

Direction of Medium

EXAMPLE: A SLINKY!

LONGITUDINAL WAVES CREATE POINTS CALLED COMPRESSIONS AND RAREFACTIONS.

•Compressions: parts where the coils are close together

•Rarefactions: parts where the coils are spread out

SOUND WAVES ARE LONGITUDINAL

EXAMPLES:

Guitar String

A drum head after being hit

THE BIG IDEA

•S8P4. Students will explore the wave nature of sound

and electromagnetic radiation.

•Explore - travel in or through (an unfamiliar

country or area) in order to learn about or

familiarize oneself with it.

CURTIS – PHYSICAL SCIENCE

S8P2

S8P4A: IDENTIFY THE CHARACTERISTICS OF ELECTROMAGNETIC WAVES.

• Identify - establish or indicate who or what

(someone or something) is.

ELECTROMAGNETIC WAVES &THE ELECTROMAGNETIC SPECTRUM

ELECTROMAGNETIC WAVES•Transverse waves without

a medium!

• (They can travel through empty space)

•They travel as vibrations in electrical and magnetic

fields.

•Have some magnetic and some electrical properties to them.

•When an electric field changes, so does the magnetic

field. The changing magnetic field causes the electric

field to change. When one field vibrates—so does the

other.

• RESULT-An electromagnetic wave.

•Electromagnetic waves travel VERY FAST – around 300,000 kilometres per second (the speed of light).

At this speed they can go around the

world 8 times in one second.

• Waves or Particles?

• Electromagnetic radiation has properties of waves but

also can be thought of as a stream of particles.

• Example: Light

• Light as a wave: Light behaves as a transverse wave which we can

filter using polarized lenses.

• Light as particles (photons): When directed at a substance light can knock electrons off of a substance (Photoelectric effect)

•Electromagnetic Spectrum—name for the range of electromagnetic

waves when placed in order of increasing frequency

RADIO

WAVES

MICROWAVES

INFRARED

RAYS

VISIBLE LIGHT

ULTRAVIOLET

RAYS

X-RAYS

GAMMA

RAYS

Notice the wavelength is

long (Radio waves) and gets shorter (Gamma Rays)

S8P4 - STUDENTS WILL EXPLORE THE WAVE NATURE OF SOUND AND ELECTROMAGNETIC RADIATION.

In your notebook:

S8P4a: Identify the

characteristics of

mechanical and

electromagnetic waves.

• Identify - establish or

indicate who or what

(someone or something) is.

SUMMARY DISCUSSION -S8P4A

Can you answer the EQ now? (P4a)

•S8P4a:

•Identify the characteristics of mechanical

and electromagnetic waves.

•

TRANSVERSE VS. LONGITUDINAL WAVES

Transverse Waves

Longitudinal Waves