Parts of a Wave… Crests= top of the wave Troughs= bottom of the wave WavelengthAmplitude (height)

Parts of a Wave…Crests= top of the wave

Troughs= bottom of the wave

Wavelength Amplitude(height)

Let’s Learn Wave Vocabulary…

Cycle

Frequency = How many waves are made per second, or cycles per second. The greater the frequency, the more waves you have.

What are Electromagnetic Waves?Electricity can be static, like what holds a

balloon to the wall or makes your hair stand on end.

Magnetism can also be static like a refrigerator magnet. But when they change or move together, they make waves - electromagnetic waves.

Electromagnetic waves are formed when an electric field combines with a magnetic field. These different waves make up the Electromagnetic Spectrum (EM)!

Question…What’s a difference between a Mechanical wave and an Electromagnetic wave?

A mechanical wave requires a medium to travel through and an EM wave doesn't.

EM waves are made up of electrical and magnetic fields together.

Electromagnetic WavesEM Waves all carry a single form of energy

called electromagnetic (radiant) energy which originates from the sun.

The electromagnetic spectrum includes, from longest wavelength to shortest: radio waves, microwaves, infrared, visible, ultraviolet, X-rays, and gamma-rays.

Electromagnetic Spectrum Weakest

Strongest Waves

Waves

As the wavelengths get shorter, the waves increase in energy. Low frequency high frequency

Radio WavesRadio waves are found at

the longest wavelengths, on the electromagnetic spectrum.

Radio waves are used to send signals to radios and communication devices.

Longest wave lengthLowest frequencylowest amount of energy

Wimpy FLV Player.exe

AM: amplitude modulatio

n

FM: frequency

modulation

Microwaves Microwaves are used in

radar because they can penetrate haze, light rain and snow, clouds, and smoke.

Used to study the universe and with communication satellites. (Mars Rover)

Cell phones and TV’s too!Microwaves are also used

to heat your food!

Evolution of the Cell Phone

*Cell phones today use a combination of both Radio and Microwaves b/c cell phones are so much more powerful today!

Better Technology

What type of wave(s) do today’s cell phones use and why?

*Cell phones today use a combination of both Radio and Microwavesb/c cell phones are

so much more powerful today!

The first cells phones only used radio waves!

Infrared WavesInfrared radiation is what

we like to describe as heat.We can't see infrared

waves, but we can feel them.

Our bodies gives off heat, so it is an emitter of infrared radiation.

Infrared waves are often used in fast food restaurants to heat food!

They are also used in satellite pictures to detect invisible infrared waves.

Infrared night visionMilitary uses night vision

goggles to see images at night.

Night vision goggles collect the tiny amounts of light and amplifies it to the point that we can easily observe the image.

Thermal Imaging This technology operates

by capturing the heat that is emitted by objects instead of simply reflected as light.

Hotter objects, such as warm bodies emit more heat that cooler objects like trees or buildings.

Visible Light WavesVisible light is the light

that we can see and thus is the only light detectable by the human eye.

White light is visible light, and it contains all the colors of the rainbow, from red to violet. (ROY G BV)

Visible Light WavesAfter observing the visible

light chart to the right, explain why I use “red waves” for my lasers pointers” instead of “violet” colored waves?Answer: I use “Red” light waves for my laser pointers because they have longer wave lengths which equals weaker frequencies (wave). Purple waves have a shorter wave length but stronger frequency which means they are more dangerous!

Ultraviolet WavesUltraviolet light is the

radiation from the sun that causes a sunburn when you have been outside too long on a sunny day.

You can't see ultra-violet light, so you can still get sunburned on a cloudy day!

Though these waves are invisible to the human eye, some insects, like bumblebees, use them to find their food!

How bees use Ultraviolet WavesWe see the flower in visible light!

Bees however see the flower in Ultraviolet light that we can’t see!

X-Ray WavesX-rays are very energetic

and are used in X-ray machines to take pictures of your bones or teeth.

Toy car in a dog’s stomach.

Gamma WavesGamma rays are the most

energetic light waves found on the electromagnetic spectrum. Gamma rays are released in nuclear reactions and particle collisions.

Gamma-rays can kill living cells so they can be used in medicine to kill cancerous cells.

Shortest wave lengthHighest frequencyHighest amount of energy

Gamma-ray bursts can release more energy in 10 seconds than the Sun will emit in its entire 10 billion-year lifetime!

Gamma RaysGamma waves can be put

to use killing cancer cells without killing the cancer patient.

This type of radiation is also used to sterilize medical instruments and bandages.

Over exposure to these waves can cause immediate death, but even low doses of gamma radiation is also associated with cell damage that causes cancer.

2. Shorter the wave length, stronger the frequency and wave!

Longer the wave length, weaker the frequency and wave!3. Gamma waves are the strongest= highest frequency and

shortest wave length!4. Between Radio and Microwaves today!5. Yes because it could cause skin cancer or brain tumors!!!6. X-rays are used because they need to be powerful enough

to penetrate through your skin and tissue to see the bones. Radio and microwave waves are too weak to penetrate the skin and tissues.

1. EM Spectrum Work Sheet

Which wave has more energy?(hint* think about amplitude and frequency)

Which wave has more energy? (hint* think about amplitude and frequency)

Wave A transfers more energy because it has a higher amplitude. (larger wave)

Frequencies are equal.

Which wave has more energy? (hint* think about amplitude and frequency)

Which wave has more energy? (hint* think about amplitude and frequency)

Wave A because it has a greater frequency.

Amplitudes (heights) are equal.

Which wave has more energy?(think about wave frequency and amplitude)

There is not enough information to determine.

A wave because it has a greater frequency.

Wave B because it has a greater Amplitude (height).

Reflection of WavesWhy do you wear sun

block at the beach? It helps to reflect the

sun’s harmful rays. SPF (sun protection factor)What color is it? Why?White because it reflects

light not absorb it!Why do football players

wear Eye black then?Black absorbs it not

reflect it!

Reflection of WavesEver seen these on

cars?Why do people use

them?Notice the color? Why

is it that color?It helps to reflect the

light and not absorb it. Helps to keep the car cooler.

Selective Absorption of EM WavesAbsorbing too much of

the sun’s radiant waves. = sunburn!

Global Warming/ Greenhouse Effect= The Earth absorbing heat from the sun’s radiant energy.

Microwave cooking- When our food absorbs microwaves and is heated up.

Absorption of Electromagnetic Waves can also be used for…

Coating on eyeglasses and sunglasses protect the eyes by permitting visible waves to pass but absorb UV waves. This is called selective absorption

Selective Absorption   Why do you wear sunglasses on a bright day?

The gift of sunglasses is that they absorb some sunlight so that it doesn't reach your eyes. If you look at a new pair of sunglasses in the store, it may have a label that reads, UV A and UV B protection.

This means that, in addition to absorbing some visible light, the glasses selectively absorb some UV rays that are harmful to your retina. It sounds so simple, but it is easy to forget that you only see the light that gets to your eyes.

Ultraviolet Wave TypesUV is divided into sub categories based on their

wavelength. UV-A waves are the longest wavelength UV waves, followed by the UV-B waves. Both UV-A and UV-B waves deliver energy to your skin that can produce sunburn damage or worse. UV-C waves have the shortest wavelength (highest frequency) of all the UV waves.

Most UV-C waves coming from the Sun do not reach the earth because they are absorbed by ozone molecules in the upper atmosphere. On the surface of the Earth, we create and use UV-C waves to kill bacteria and sterilize things such as the goggles that you wear in science class.

Which Jell-O will selectively absorb more energy from the

laser?

Red Jell-O Blue Jell-O

Where you right?Red Jell-O Blue Jell-

O

The Blue Jell-O absorbs more energy!