Unit 3: Waves · •Mechanical waves - •Vibration ... • X-RAYS - electromagnetic waves whose...
Transcript of Unit 3: Waves · •Mechanical waves - •Vibration ... • X-RAYS - electromagnetic waves whose...
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