1. The Power of Waves

2. Parts of a Wave… Crests= top of the wave Troughs= bottom of the wave
Wavelength
Amplitude
(height)
Troughs= bottom of the wave

3. Let’s Learn Wave Vocabulary…
Frequency = How many waves are made per second, or cycles per second.
The greater the frequency, the more waves you have.
Cycle

4. Frequency of Waves
If ten waves are made per second, then the frequency is said to be ten cycles per second, written as 10 cps.
Usually, we use the unit Hertz to state frequency.
Anyone ever heard of Hertz before?
The unit Hertz is abbreviated this way:
1 Hertz = 1 Hz
1 cps = 1 Hertz

5. 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!

6. 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, X-rays, and gamma-rays.

7. Question…
What’s the 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.

8. Electromagnetic Spectrum
Weakest Strongest
Waves Waves
As the wavelengths decrease, the wave increases in energy.
Low frequency high frequency

9. 2. Shorter the wave length, stronger the frequency and wave! 1.
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!
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 waves are too weak to penetrate the skin and tissues.

10. AM: amplitude modulation
FM:
frequency modulation
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

11. 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!
Microwaves are also used to heat your food!

12. 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 satellite pictures to detect invisible infrared waves.

13. Infrared night vision
Military 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.

14. 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.

15. 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 colors of the rainbow, from red to violet.

16. Visible Light Waves
After observing the visible light chart to the right, explain why I use “red light waves” for my lasers pointers” instead of purple light 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 means they are more dangerous!

17. 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, some insects, like bumblebees, use them to find their food!

18. How bees use Ultraviolet Waves
We see the flower in visible light!
Bees however see the flower in Ultraviolet light that we can’t see!

19. 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 looked like in X-rays on April 27th, 2000.

20. 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 lifetime!

21. 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 radiation is also associated with cell damage that causes cancer.

22. Which wave has more energy?

23. Which wave has more energy?
Wave A transfers more energy because it has a higher amplitude. (larger wave)
Frequencies are equal.

24. Which wave has more energy?

25. Which wave has more energy?
Wave A because it has a greater frequency.
Amplitudes (heights) are equal.

26. Which wave has more energy?

27. 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).

28. 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 it!

29. Reflection of Waves Ever 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.

30. 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 microwaves and is heated up.

31. Green house Effect

32. 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

33. 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.

34. 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 bacteria and sterilize things such as the goggles that you wear in science class.

35. Refraction
Refraction is the change in direction of a wave due to a change in its speed.

36. Which Jell-O will selectively absorb more energy from the laser?
Red Jell-O
Blue Jell-O

37. Where you right? The Blue Jell-O absorbs more energy! Red Jell-O

38. 1. When a wave strikes a substance, its energy will be absorbed.
AGREE DISAGREE
2. When a wave is absorbed by a substance, its energy is used up.
3. All frequencies of EM waves are absorbed by the same substances.
4. Energy that has been absorbed by a wave can be re-emitted by the substance.