10/4 & 10/5 - 7th Grade Agenda

Learning Objective: Learn the difference between amplitude and frequencyCollect: Reading & Note Taking p.29 – 32Chap 1 TestOptical IllusionsVideo: WavesClass Reading: p. 40 - 41HW: Reading & Notetaking : p. 33- 34

Daily Reflection

• Prompt: What is the crest of the wave? What is the trough of a wave? Draw a wave and label crest and trough of a wave.

Wave

• A wave is a disturbance that transfer ene_____ from place to place.

• Who can give me examples of waves?

rgy

Is light a wave?

• Yes

• But why?

Picture of Light Wave

• Image of a pulse of light that is 2.5 billionths of a millionth of a second long

Energy

• In science, energy is defined as the ability to do wo___.rk

Medium

• The material through which a wave tra____ is called a medium

• Who can give me examples of medium?

vels

Does Light Waves need a medium?

• Scientist first thought that Light needed to travel through a medium. So they invented the idea of aether in space.

• They look for aether in outer space but they found nothing.

• So, Light Waves can travel without a medium even in a Vacuum of outer space.

Crest

• Hi___ point of a wave is called a crest

gh

Trough

• L___ point of a wave is called a trough

ow

Amplitude

• Amplitude is the max______ distance that the particles of medium carrying the wave move away from their rest positions.

• Which rope has higher amplitude?

imum

Wavelength

• The distance between two corresp______ parts of a wave is its wavelength.

• Which rope has longer wavelength?

onding

Frequency

• Wave frequency is the num_____complete waves that pass a given point in a certain amount of time

ber

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

Optical Illusions