PHYSICAL SCIENCEWaves and Electromagnetic Radiation

Bell Ringer1.) The higher the ________ the more energy is in the wave.

2.) In ___________ waves, the medium vibrates at right angles to the direction of wave travel

3.) Wavelengths of the ER spectrum span from the size of a _______ field to sizes just a little bit larger than an _____

Objectives For Today:

•Today we are:•Building an understanding of the electromagnetic spectrum

•Defining the relationship between wave AMPLITUDE and wave ENERGY

Agenda/Announcements!

•Bell Ringer

•Electromagnetic Radiation and the light spectrum

•Build wave generator

•Finish work pages from yesterday

•HOMEWORK: Correction: Worksheets are due TOMORROW.

What are waves?

Electromagnetic Spectrum

© 2000 Microsoft Clip Gallery

Electromagnetic Spectrum

•Visible Spectrum – Light we can see•Roy G. Biv – Acronym for Red, Orange, Yellow, Green, Blue, Indigo, & Violet.

•Largest to Smallest Wavelength.

Modulating Radio Waves

•Modulation - variation of amplitude or frequency when waves are broadcast•AM – amplitude modulation

• Carries audio for T.V. Broadcasts•Longer wavelength so can bend around hills

•FM – frequency modulation •Carries video for T.V. Broadcasts

© 2000 Microsoft Clip Gallery

Short Wavelength Microwave

•Invisible Spectrum (Cont.)•Infrared Rays

•Def – Light rays with longer wavelength than red light.

•Uses: Cooking, Medicine, T.V. remote controls

Animals that can sense infra red

•Many vipers and beetles can sense infra-red rays.

Electromagnetic Spectrum

•Invisible spectrum (cont.).•Ultraviolet rays.

•Def. – EM waves with frequencies slightly higher than visible light

•Uses: food processing & hospitals to kill germs’ cells

•Helps your body use vitamin D.

The Mantis Shrimp – Different spectra

• Watch video

Electromagnetic Spectrum

•Invisible Spectrum (Cont.)•X-Rays

• Def. - EM waves that are shorter than UV rays.• Uses: Medicine – Bones absorb x-rays; soft tissue does not.

• Lead absorbs X-rays.

Electromagnetic Spectrum

•Invisible spectrum (cont.)•Gamma rays

•Def. Highest frequency EM waves; Shortest wavelength. They come from outer space.

•Uses: cancer treatment.

LIGHT: Refraction of Light

•Refraction – Bending of light due to a change in speed. •Index of Refraction – Amount by which a material refracts light.

•Prisms – Glass that bends light. Different frequencies are bent different amounts & light is broken out into different colors.

Refraction (Cont.)

Ordering Activity

Who was following along?

Order the students by wavelength.

AMPLITUDE vs. ENERGY

•Slinky – try making the amplitude twice as large...3 times as large…. What do you notice?

AMPLITUDE vs. ENERGY

•SQUARED relationship. • IMPORTANT! What does this mean?

Wave Generator

•Each group will add 10 straws to the wave generator. When finished, these will be used for review on Friday

•EACH STRAW NEEDS:•A paperclip on EACH end

•To be centered on the tape (IMPORTANT!)

•To be evenly spaced (about 1cm in between straws!)

Wave Generator

•Each group will add 10 straws to the wave generator. When finished, these will be used for review on Friday

•EACH TABLE ASSEMBLY LINE:• Person 1 – Grab straw, pass to person 2

• Person 2 – Apply paperclip to one end – pass to person 3

• Person 3 – Apply paperclip to other end – pass to person 4

• Person 4 – apply straw to wave generator (start a top moving down)• *Person 1 can help apply straws since there will probably be a

bottleneck with person 4

FINISHING HMWK

•Finished Hmwk goes in the Blue Folder. Thursday is the absolute last day it will be accepted

Exit slip

•Give the wave generator a push at the top.

•How do you know that this is a transverse wave (think right angles…)

•Try changing the amplitude. What do you notice about the energy required to change the amplitude?