Topic3: Electromagnetic Radiation(EMR)

  • EMR - A wave that consists of a changing electric and magnetic field that travels at right angles to one another

More vocab

  • Cycle - One completed vibration of a wave(one crest and one trough)

  • Wavelength - Length of one cycle(ex. one maximum and one minimum)

    • in Meters and a tent looking symbol

  • Frequency - # of cycles per second

    • in Hz(hertz) and f symbol

*Wavelength and frequency are opposite

  • High frequency = high energy = short wavelength

  • The waves of alternating electric and magnetic fields that all move through space at the “speed of lights”(called “C”)

How are radio waves different from x-rays?

  • Different types of radiations will have differences sources, wavelengths, and frequencies

    • Because EMR have different frequencies and wavelengths, this means they carry different amounts of energy photons

  • When looking at the diagram in the data booklet:

    • EMR to the left of visible light are non-ionizing(not cancerous)

    • Right of visible light are ionizing(cause cancer)

Types of EMRs

  • Radio waves

    • Lowest energy

    • Source: vibration of e- within electric circuits

    • Penetrating ability: CANNOT penetrate metal so an antenna is sometimes needed

      • On cars before in old old times lol

    • Not ionizing

    • Applications: Mostly used for communication

      • ex) Cell phone radio

      • Can also be used for magnetic resonance imaging(MRI’s)

        • Used to locate tumors

  • Microwaves

    • Source: High frequency vibrations of e- within specialized circuits

    • Penetrating ability: Hazardous to humans due to the high water content of living tissues

      • Exposure leads to cataracts

      • Can travel through air, smoke, rain, etc

    • Not ionizing

    • Applications: Heating food

      • Used in radar, GPs, and satellites

  • Infrared “heat”

    • Source: Emitted from hot objects

    • Penetrating ability: Can burn human tissue

    • Not ionizing

    • Applications: Used in motion detectors, heat seekers, remote controls, and other wireless devices

  • Visible light

    • Source: Emitted by objects that are hot

      • Ex)Sun, light bulb, and a fire

    • Penetrating ability: Can penetrate through air as well as the lenses of our eyes

    • Not ionizing

    • Applications: Allows us to see objects

      • Photosynthesis to occur in plants

  • Ultraviolet

    • Source: Very hot objects

    • Penetrating ability: UVA and UVB can penetrate the ozone layer. UVC is absorbed by the ozone

      • May cause abnormally fast cell division(mitosis) - cancer(melanoma)

      • UV is ionizing and can kill bacteria by breaking down DNA

      • Can also cause aging of the skin

    • Some types of UV are ionizing

      • Anything to the right of visible light on the spectrum is ionizing

    • Applications: Tanning beds and sterilize equipment

  • X-rays

    • Source: Fast moving e- striking a metal target

    • Penetrating ability: Can penetrate body tissue

    • ionizing

    • Applications: X-ray teeth and bones, and radiation therapy

  • Gamma Rays

    • Highest energy

    • Source: Emitted from radioactive material

    • Penetrating ability: Can penetrate metals

      • Can cause mutations and cell death

    • ionizing

    • Applications: Sterilization of food(irradiation) and medical imaging

More EMR vocab! Light

  • Reflected light - What bounces off an object

    • Angle of incidence = angle of reflection

  • Refracted light - when EMR waves bend when they go from one medium to another

  • Diffraction - the scattering of a wave as it passes an obstacle

  • Polarization - means to confine a wave to vibrate only in one direction

    • This is used in polarized sunglasses to reduce glare