Transcript 4/20 & 4/21 - 7th Grade Agenda

10/12 - 7th Grade Agenda
Collect: HW: Reading & Note Taking : p.
33- 34
Waves and Electromagnetic Spectrum
Video: Electromagnetic Energy
Chap1 Test & Reflection for Absent
students
Class Reading: p. 42- 45
HW: Reading & Note Taking : p. 35- 36
Wave
• A wave is a
disturbance that
transfer ene_____
rgy
from place to
place.
• Who can give me
examples of
waves?
Medium
• The material through which a
vels is called a medium
wave tra____
• Who can give me examples of
medium?
Crest
gh point of a wave is called a
• Hi___
crest
Trough
ow point of a wave is called a
• L___
trough
Amplitude
imum distance that
• Amplitude is the max______
the particles of medium carrying the wave
move away from their rest positions.
• Which rope has higher amplitude?
Wavelength
• The distance between two
corresp______
onding parts of a wave is
its wavelength.
• Which rope has longer wavelength?
Frequency
• Wave frequency is the
num_____complete
waves that
ber
pass a given point in a certain
amount of time
Electromagnetic Wave
• An electromagnetic wave
consists of vibrating electric and
magnetic field that move through
space at the speed of lig____
ht
What are some examples of
electromagnetic waves?
•
•
•
•
•
•
•
Radio Waves
TV Signals
Microwaves
Infrared rays
Light
Ultraviolet rays
X-Ray
How fast do electromagnetic
waves travel?
•
•
•
•
It is the fastest thing in the universe
300,000 km per second
186,000 miles per second
It takes 8 minutes for light to travel from the sun
to the earth
• It takes 3 million years for light to travel from the
nearest galaxy (andromeda) to the earth
Electromagnetic Wavelength
How do we use Radio Waves?
• Radio & TV
signals
• Microwave Oven
• Radar
• MRI
• Cell phone
Using Microwaves
• Why do you see sparks you put metal objects in
a microwave?
• Because of the build up of electrical energy in
the metal
• The long wave length of Microwaves can pass
right through glass and plastic. That is why
microwaves do not heat glass and plastic
containers.
How do we use Infrared Rays?
• Conventional Oven
• Heat Lamps
• Thermograms
Visible Light makes up only a
small part of the electromagnetic
spectrum