Catchin’ Waves

WAVES

Catchin’

Waves

Waves

⚫

This surfer is

using the energy

of the wave to

propel himself

There are two types of waves

⚫

Transverse Waves

Example: Ocean Waves

⚫

Longitudinal Waves

Parts of a Wave…

Crests=

Troughs=

Let’s Learn Wave Vocabulary…

Cycle

Frequency = How many waves are made per second, or cycles per second.

Frequency of Waves

⚫ Usually, we use the unit Hertz to state frequency.

⚫ Anyone ever heard of Hertz before?

⚫ Stereos, T.V.’s, computers all use Hertz.

⚫ The unit Hertz is abbreviated this way:

⚫ 1 Hertz = 1 Hz

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

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.

Electromagnetic Waves

⚫ EM 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,

Electromagnetic Spectrum

Weakest Strongest

Waves Waves

As the wavelengths decrease, the wave increases in energy.

Radio Waves

⚫ Radio 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 length

⚫ Lowest frequency

⚫ lowest amount of energy

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.

⚫ Cell phones and TV’s too!

Evolution of the Cell Phone

*Cell phones today use a

combination of both Radio and

What type of wave(s) do today’s

cell phones use and why?

⚫ *Cell phones today use a combination of both Radio and Microwaves

⚫ b/c cell phones are so much more powerful today!

Infrared Waves

⚫ Infrared 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

Infrared night vision

⚫ Military uses night vision goggles to see images at night.

Thermal Imaging

⚫ This technology operates by capturing the heat that is emitted by objects

instead of simply reflected as light.

Visible Light Waves

⚫ Visible 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

Visible Light Waves

⚫ After 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), and they can travel farther. Purple waves have a shorter wave length but stronger frequency which

Ultraviolet Waves

⚫ Ultraviolet 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,

How bees use Ultraviolet Waves

Bees

X-Ray Waves

⚫ X-rays are very energetic

and are used in X-ray

machines to take pictures of your bones or teeth.

⚫ The Sun also emits X-rays - here is what the Sun

Gamma Waves

⚫ Gamma 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 length ⚫ Highest frequency

⚫ Highest amount of energy

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

Gamma Rays

⚫ Gamma 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

Which wave has more energy?

Which wave has more energy?

(hint* think about amplitude and frequency)

⚫

Wave A transfers

more energy

because it has a

higher amplitude.

(larger wave)

Which wave has more energy?

Which wave has more energy?

(hint* think about amplitude and frequency)

⚫

Wave A because it

has a greater

frequency.

Which wave has more energy?

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

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.

Reflection of Waves

⚫ Why 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

Reflection of Waves

⚫ Ever seen these on cars?

⚫ Why do people use them?

⚫ Notice the color? Why is it that color?

Example of

Reflection

⚫ Grand central station, NYC (Whisper Gallery)

Selective Absorption of EM Waves

⚫ Absorbing 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

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

   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

Ultraviolet Wave Types

⚫ UV 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

Which Jell-O will selectively absorb

more energy from the laser?

Were you right?

Red Jell-O Blue Jell-O