Science - 2nd Quarter

EM waves

Electromagnetic waves

transverse waves, perpendicular to the direction of wave propagation, can travel thru a vacuum and does not require a medium, propagate thru space

Speed of Light

3×10^8 m/s

Crest

-Highest point above equilibrium (rest position)

-peak of the wave

Trough

Lowest point, opposite direction to the crest

Amplitude

-Maximum displacement
-How far the particles of the medium move
- the larger this one is the more energy it carries

wavelength

-distance between 2 consecutive crest or 2 consecutive troughs
-represents one complete wave cycle
-measured in meters

Frequency

-wave cycles pass a given point per unit of time
-inversely related to wavelenght
-measured in Hertz

Node

point where wave has zero amplitude

Electromagnetic radiation

energy emitted or radiated by charged particles

electromagnetic spectrum

entire range of electromagnetic radiation

William Gilbert

-studied magnetism and coined term ELECTRICUS to describe materials that attracted small objects

-laid foundation for study of ELECTRICITY AND MAGNETISM as distinct phenomena

Hans Orsted

discovered that an ELECTRIC CURRENT IS SURROUNDED BY MAGNETIC FIELD

Michael Faraday

discovered MOVING WIRE thru a magnetic field could produce an electric current.

-ELECTROMAGNETIC INDUCTION

Joseph Henry

-current produced by magnetic field is an induced current
-INDEPENDENTLY discovered the phenomenon of electromagnetic induction similar to FARADAYS work

James Maxwell

culmination of previous discoveries in electromagnetism

discovered SCIENTIFIC THEORY
electric and magnetic fields interact

ELECTROMAGNETIC WAVES TRAVEL AT SPEED OF LIGHT

Heinrich Hertz

-Production of RADIOWAVES
-UNIT OF FREQUENCY OF RADIOWAVE:
1 cycle or second (Hertz)

Radiowaves

-non ionizing

-modern communication, radio broadcasts, wifi, television, communication, navigation (GPS), wifi nets

Microwaves

-non ionizing radiation but prolong exposure can cause thermal effects like heating of tissue, burns, cataracts, and internal organ damage
-used to cook and heat food, also used as cellphones and wifi, radar systems, satellite communication, bluetooth devices

Es’hailSat

Qatar Satellite Company meaning star Canopus

Infrared

Heat radiation
non ionizing
remote controls and thermal cam, med therapy, sec systems

Visible light

detectable by the human eye
allow us to see the world around us
photography, imaging, lighting, communication, and photosynthesis, lasers

Uv rays

-sunburn, skin aging, cancer risks

-sterilization and disinfection, medical applications, forensic science

UV- A

penetrates to skin (dermis)
skin aging, wrinkles, tanning, and contributes skin cancer

UV-B

Affects outer layer (epidermis)
sunburn, skin cancer, vitamin D production

UV-C

absorbed by ozone layer (doesnt reach earth)
highly harmful used for disinfection purposes

X-rays

Ionizing radiation - has enough energy to remove electrons from atoms and molecules potentially causing significant biological damage
Can pass thru soft tissues, making them useful for medical imaging
security scanning, industrial testing, astronomy

Gamma Rays

Nuclear reactions, radioactive decay and other high-energy processes

ionizing radiation- can cause DNA damage, mutations, and increased cancer risk
used in radiation therapy to treat cancer

How to protect against gamma radiation

thick layer of dense materials like lead and concrete

Plank’s constant

6.63×10^-34 J.s