Chapter 9 Lesson 1

Waves of the Electromagnetic Spectrum

Standards• SC.7.P.10.1: Illustrate that the sun’s energy arrives as radiation

with a wide range of wavelengths, including infrared, visible, and ultraviolet, and that white light is made up of a spectrum of many different colors. (L)• SC.7.P.10.3: Recognize that light waves, sound waves, and other

waves move at different speeds in different materials. (L)• SC.8.E.5.11: Identify and compare characteristics of the

electromagnetic spectrum such as wavelength, frequency, use, and hazards and recognize its application to an understanding of planetary images and satellite photographs. (H)• SC.7.P.10.2: Observe and explain that light can be reflected,

refracted, and/or absorbed. (H)

Learning Goal

• Students will be able to identify, compare and contrast characteristics of the electromagnetic spectrum and its interaction with matter.

• How does the sun’s energy arrive on earth?• How do electromagnetic waves compare?• What makes up the electromagnetic spectrum?

Essential Questions

• The sun’s energy arrives on Earth as electromagnetic radiation.

• Vocabulary• Radiation – the transfer of energy by electromagnetic waves• *Electromagnetic wave – a wave that can transfer electric and magnetic

energy

How Does the Sun’s Energy Arrive on Earth?

How Does the Sun’s Energy Arrive on Earth?

Electromagnetic Wave Animation

• What can electromagnetic waves travel through?• Empty Space• Gases (ex. Air)• Liquids (ex. Water)• Solids

How Does the Sun’s Energy Arrive on Earth?

• What can electromagnetic waves travel through?• Empty Space (Contains no matter)• Gases (Contains matter)• Liquids (Contains matter)• Solids (Contains matter)

• *Medium – a substance that contains matter through which waves can travel through• EM. Waves do not require a medium to travel through.

How Does the Sun’s Energy Arrive on Earth?

• *Characteristics of EM. Waves• Electrical and magnetic properties• Electric and magnetic field are at right angles (90°) to each other• Does not require a medium to travel through• Travels fastest in: vacuum (empty space) > gas > liquids > solids

How Does the Sun’s Energy Arrive on Earth?

• *Crest – highest most point on a wave• *Trough – lowest most point on a wave

Characteristics of Waves

Crest

Trough

Crest Crest

Trough Trough

• *Wavelength - the distance between the crest of one wave to the crest of another wave

Characteristics of Waves

Wavelength

Wavelength

• *Amplitude – the maximum displacement or vibration of a particle in a wave.

Characteristics of Waves

Amplitude

Amplitude

• What is a complete wave?

Characteristics of Waves

Characteristics of Waves

• *Frequency - the number of complete waves that pass a given point in a certain amount of time.• Wavelength - the distance

between the crest of one wave to the crest of another wave

Characteristics of WavesHigh Frequency

Low Frequency

Short Wavelength

Long Wavelength

• All EM. Waves travel at the same speed in a vacuum. They have different wavelengths and frequencies.

How Do EM. Waves Compare?

• The EM. Spectrum is made up of radio waves, microwaves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays.

What Makes Up the EM. Spectrum?

RADIO WAVESRADIO WAVES

Have the longest wavelengths and

lowest frequencies of all the

electromagnetic waves.

Global Positioning Systems (GPS) measure the time it takes a radio wave to travel from several satellites to the receiver,

determining the distance to each satellite.

A radio picks up radio waves through an antenna and converts it to sound waves.– Each radio station in an area broadcasts at a different

frequency. • # on radio dial tells frequency.

MRI (MAGNETIC RESONACE IMAGING)

Uses Short wave radio waves with a magnet to create an image.

MICROWAVESMICROWAVES

Have the shortest wavelengths and the highest frequency of the radio waves.

Used in microwave ovens.•Waves transfer energy

to the water in the food causing them to vibrate which in turn transfers energy in the form of heat to the food.

RADAR (Radio Detection and Ranging)• Used to find the speed of an

object by sending out radio waves and measuring the time it takes them to return.

INFRARED RAYSINFRARED RAYS

Infrared= below redShorter wavelength

and higher frequency than

microwaves.

You can feel the longest ones as warmth on your

skinWarm objects give off

more heat energy than cool objects.

Thermogram—a picture that shows regions of different temperatures in the body. Temperatures are calculated by the amount of infrared

radiation given off.

Therefore people give off infrared rays.

Heat lamps give off infrared waves.

VISIBLE LIGHTVISIBLE LIGHTShorter wavelength and higher

frequency than infrared rays.Electromagnetic waves we can

see.Longest wavelength= red

lightShortest wavelength= violet

(purple) light

When light enters a new medium it bends

(refracts). Each wavelength bends a

different amount allowing white light to

separate into it’s various colors

ROYGBIV.

ULTRAVIOLET RAYSULTRAVIOLET RAYS

Shorter wavelength and higher

frequency than visible light

Carry more energy than visible light

Used to kill bacteria.

(Sterilization of equipment)

Too much can cause skin cancer.Use sun block to protect against (UV rays)

Causes your skin to produce

vitamin D (good for teeth and

bones)

X- RAYSX- RAYSShorter wavelength

and higher frequency than UV-

raysCarry a great amount

of energyCan penetrate most

matter.

Bones and teeth absorb x-rays. (The light part of an x-ray image indicates a place where the x-ray was absorbed)

Too much exposure can cause cancer

(lead vest at dentist protects organs from

unnecessary exposure)

Used by engineers to check for tiny cracks in structures.– The rays pass

through the cracks and the cracks appear dark on film.

GAMMA RAYSGAMMA RAYS

Shorter wavelength and higher frequency than X-

raysCarry the greatest amount

of energy and penetrate the most.

Used in radiation treatment to kill cancer cells.

Can be very harmful if not used correctly.

The Incredible Hulk was the victim of gamma radiation.

Exploding nuclear

weapons emit gamma rays.

Brief SUMMARYA. All electromagnetic waves travel at the same speed.

(300,000,000 meters/second) in a vacuum.B. They all have different wavelengths and different

frequencies.– Long wavelength-lowest frequency– Short wavelength highest frequency– The higher the frequency the higher the energy.

Electromagnetic Spectrum Foldable

Activity

Step 1: Fold the paper given to you in half hot dog style.

Step 2: Using a ruler, make 6 marks across your paper of about equal distance (40 cm apart) along the crease.

Step 3: Cut from the side of the paper towards each mark to make flaps. Do not cut past the crease (fold) on the paper.

Step 4: Draw the waves illustrated below on your paper.

Instructions:

1. On the outer flaps above the wave, label the appropriate EM. Wave from left to right

2. Above or below the wave you drew, label which side has the following:a. long/short wavelengthb. high/low frequency c. high/low energy

3. On the back of the flap, write:a. Characteristics b. Usesc. Useful and/or hazardous

Instructions:

1. On the outer flaps above the wave, label the appropriate EM. Wave from left to right

Outside FlapsRa

diow

aves

Mic

row

aves

Infr

ared

Ray

s

Visi

ble

Ligh

t

Ultr

avio

let R

ays

X-ra

ys

Gam

ma

Rays

Instructions:

2. Above or below the wave you drew, label which side has the following:a. long/short wavelengthb. high/low frequency c. high/low energy

Outside FlapsRa

diow

aves

Mic

row

aves

Infr

ared

Ray

s

Visi

ble

Ligh

t

Ultr

avio

let R

ays

X-ra

ys

Gam

ma

Rays

Long WavelengthLow FrequencyLow Energy

Short WavelengthHigh FrequencyHigh Energy

Instructions:

3. On the back of the flap, write:a. Characteristics b. Usesc. Useful and/or hazardous

Radiowaves

A.Longest wavelengths, Lowest frequenciesB.Used in broadcasting to carry signals for radio programsC.Useful

Microwaves

A. Have shorter wavelengths and higher frequencies than radio waves

B. Used in microwaves to cook food, cellular phones, radar guns

C. Useful

Infrared Rays

A. Have shorter wavelengths and higher frequencies than microwaves

B. Used in heat lamps to keep things warm. Also used in infrared cameras to detect heat.

C. Useful

Visible Light

A. Have shorter wavelengths and longer frequencies than infrared rays.

B. White light can be separated into red, orange, yellow, green, blue, and violet (ROY G BIV)

C. Red has the longest wavelength and lowest frequency. Violet has the shortest wavelength and highest frequency.

Ultraviolet Rays

A. Shorter wavelengths and higher frequencies than visible light.

B. Energy is great enough to damage or kill living cells. Too much exposure can burn your skin. Small doses can cause skin cells to produce vitamin D.

C. Useful and Hazardous

X-rays

A. Shorter wavelengths and higher frequencies than ultraviolet rays

B. Can penetrate most matter. Can be used to make images of bones and teeth. Too much exposure can cause cancer.

C. Useful and hazardous

Gamma Rays

A. Shortest wavelengths and highest frequenciesB. Most penetrating of all waves. Can be used to examine

the body’s internal structures.C. Useful and hazardous.

Chapter 9 Lesson 2

Reflection

Learning Goal

• Students will be able to identify, compare and contrast characteristics of the electromagnetic spectrum and its interaction with matter.

• What are the kinds of reflection?

Essential Questions

• Light travels in straight lines as rays

• Each line is calleda light ray

Things You Need to Know About Light

What’s the difference in reflection?

What’s the difference in reflection?

What’s the difference in reflection?

• The two ways in which a surface can reflect light are regular reflection and diffuse reflection.

What Are the Kinds of Reflection?

What’s the difference in reflection?

Regular Reflection

Diffuse Reflection

• Regular reflection – reflection that occurs when parallel rays of light hit a smooth surface and all reflect at the same angle.• Diffuse reflection - reflection that occurs when parallel rays of

light hit an uneven surface and all reflect at different angles.

What Are the Kinds of Reflection?

Chapter 9 Lesson 3

Refraction

Learning Goal

• Students will be able to identify, compare and contrast characteristics of the electromagnetic spectrum and its interaction with matter.

• What happens when light hits an object?• What factors affect the speed of an electromagnetic wave?

Essential Questions

• When light hits an object, it can be reflected, refracted, and/or absorbed.

What absorbs more light? Your science table or a window?• The more transparent an object is, the less light it will absorb.• Objects absorb all but one specific color (specific

wavelength/frequency). That one specific color is reflected, which is why objects appear to be that color.

What Happens When Light Hits an Object?

• We already know how light reflects. What does refracted mean?

What Happens When Light Hits an Object?

Have you ever seen something like this before?

What about this?

The light rays are bending!

What has happened to the light rays coming from the straw?

• Refraction – the bending of light rays as they pass from one medium to another.

Why do you think the light ray depicted to the right are bending that way as they passfrom air to water to glass and back into air?

What Happens When Light Hits an Object?

What Happens When Light Hits an Object?

The water droplet is transparent,so the light does not get absorbed.

When white light enters thewater droplet, each color isrefracted by a different amount.

Each color of lightreflects off the back surface of thewater droplet.

Each color of light is refractedagain as it exits the water droplet.

• The speed of an electromagnetic wave through a substance is determined by the substance’s physical properties.

What Factors Affect the Speed of an Electromagnetic Wave?

• Pages 311-312 #1-6, 13-15• Page 313

Class work/Homework