PHYSICAL SCIENCEWaves and Electromagnetic Radiation

Bell Ringer1.) Get Bell Ringer from school computer since it didn’t save…

Objectives For Today:

•Today we are:

•Discussing properties of electromagnetic radiation: Reflection, Absorption, Transmission

Agenda/Announcements!

•Bell Ringer

•Electromagnetic Radiation properties

•Finish work pages from yesterday

•HOMEWORK: Worksheets are due TODAY.

What are waves?

The Big Three: BrainstormingDiscuss with a partner. What are the best examples you can think of for:

1.) A wave being reflected

2.) A wave being absorbed

3.) A wave being transmitted through a medium

Discuss at your table. You have 5 MINUTES! Write your answers (For you and your partner) on your post-it note

5 minute sand timer

5 minutes

End

The Big Three: Brainstorming

Place your post-it notes under the appropriate categories on the board!

Class discussion: What were some of your best ideas?

The Big Three: Reflection

Waves can be reflected

Reflection usually comes to mind when we think about light and mirrors. However, all waves can be reflected.

The Big Three: Reflection

Reflection Examples:Laser rangefindingHam RadiosRadarSonar

The Big Three: Reflection•Reflection is the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated.

•The law of reflection says that for specular reflection the angle at which the wave is incident on the surface equals the angle at which it is reflected.

•In acoustics, reflection causes echoes and is used in sonar. In geology, it is important in the study of seismic waves. Reflection is observed with surface waves in bodies of water.

The Big Three: Absorption

Waves can be absorbed by an object – objects that absorb waves tend to have an increase in heat energy

The Big Three: Absorption

Radar Absorbent Material

Urban Heat Island Effect

Blacktop Pavement

Singing Booths

The Big Three: Absorption

absorption of electromagnetic radiation is the way in which the energy of a photon is taken up by matter, typically the electrons of an atom.

The electromagnetic energy is transformed into internal energy of the absorber.

Example: thermal energy

The reduction in intensity of a light wave propagating through a medium by absorption of a part of its photons is often called attenuation.

The Big Three: Transmission

Waves can be transmitted through different mediums depending on the power of the wave, the wavelength and the density of the object.

The Big Three: Transmission

Ground Penetrating Radar

Directed Sound Denial Systems

Radio Stations

X-Rays

MRI machines

CT scans