Electromagnetic Radiation

• Light energy.
• Has electrical and magnetic properties.
• Different than radioactivity (energy let off when nucleus with too many protons and neutrons starts to fall apart).

<aside> ⚛️ Photon: a “particle” of electromagnetic radiation.

</aside>

Electromagnetic Spectrum

• Know the relative ranking of types of radiation in the electromagnetic spectrum.

• Radio waves:

  • Low frequency means less photons hit per second.
  • No damage.
  • About the size of buildings.

• Microwaves:

  • Not dangerous radiation.
  • Works to heat food by bombarding water with waves to make molecules vibrate. Water transfers the energy to the rest of the food.
  • About the size of grains of sugar.

• Infrared:

  • “Infra” means below.
  • About the size of protozoan.

• Visible light:

  • Small part of the electromagnetic spectrum that humans can see.
  • About the size of bacteria.

  Red	Orange	Yellow	Green	Blue	Violet
  Long wavelength					Short wavelength
  Low frequency					High frequency
  Low energy					High energy

• Ultraviolet:

  • Higher than violet.
  • Dangerous (depending on dosage and genetics). Causes skin cancer.
  • About the size of molecules.

• X-ray:

  • Dangerous for living organisms.
    • Block with metallic lead (dense) to protect soft tissues.
  • About the size of atoms.

• Gamma Ray:

  • Dangerous in low doses (e.g. nuclear explosion).
  • Tiny and a lot hit in a given second.
  • Can fit through skins (smaller than the bonds in skin).
  • About the size of atomic nuclei.

Light Equations

<aside> ⚛️ Light: $c = \lambda \nu$

• c = speed of light = $2.998 \times 10^8$ m/s.

• $\lambda$ (lambda) = wavelength in meters.

• $\nu$ (nu) = frequency in $s^{-1}$ or hertz (Hz). </aside>

• Watch the units! Use metric conversions to use equation with the correct units.

  • 100 cm = 1 m.
  • $10^9$ nm = 1 m.

• Wavelength and frequency have an inverse relationship.