Physics of Waves and Radiation

Non-Ionizing Radiation

• Radio wave, Microwave, Infrared, and Visible Light are types of non-ionizing radiation.

Ionizing Radiation

• X-ray and Gamma Ray are types of ionizing radiation.

Mechanical Waves

• Medium: Liquid, Solid, or Gas.
• Wave Type:
  • Transverse Wave: moves in a right angle direction.
  • Compressional or Longitudinal Wave: vibrates parallel to the motion of the pulse, transfers sound.
  • Two types of Longitudinal waves:
    • Compression: close together.
    • Rarefaction: spread apart.

Wave Frequency

• Measured by how many complete waves pass a fixed point in a certain amount of time.
• Frequency has an inverse relationship with wavelength: Higher frequency = Shorter wavelength.
• Wave speed (r) = Frequency (Hz) x Wavelength (m).

Types of Waves

• Slinky Wave: energy is being transferred back and forth.
• Transverse Wave: frequency has an inverse relationship with wavelength.
• Rarefaction: wave enters a new medium at an angle, causing bending of waves due to a change of speed.
• Reflection: object or wave hits a surface through which it cannot pass, it bounces back.
• Diffraction: wave moves around/through an opening in a barrier, it bends and spreads out.
• Interference: occurs when two or more waves meet while traveling through the same medium.
  • Constructive – Combine wave, continues.
  • Destructive – When crest meets trough, they cancel.
• Standing Wave: incoming waves/reflected waves with the right frequency produce a wave that looks standing still.

Light

• Produced in two ways:
  • Incandescence: caused by heat.
  • Luminescence: caused by the movement of atoms.
• Types of Luminescence:
  • Chemiluminescence: chemical reaction.
  • Bioluminescence: caused by organisms.
  • Fluorescence: light ceases when external excitation stops.
  • Phosphorescence: persists even after the removal of external excitation.
• Types of Eclipse: Lunar and Solar.
• Brightness of light:
  • Photometry: measures luminous intensity (I) in cd (Candela) and luminous flux (f) in Im (Lumens).

Endocrine System

• Disorders:
  • Osteoporosis: mineral density of the bone is reduced, making it brittle and porous.
  • Goiter: abnormal enlargement of the thyroid gland.
  • Gigantism: abnormal increase in height associated with too much secretion of growth hormones.
  • Dwarfism: growth hormones in the pituitary gland are insufficient, resulting in short stature.
• Glands:
  • Adrenal: affects metabolism, immune system, and blood pressure, stress reaction.
  • Pancreas: regulates blood sugar levels, reproductive.
  • Pineal: regulates the biological clock in some animals.

Menstruation Cycle

• Phases:
  • Follicular phase: starts on day 1 of menstruation, ends with ovulation (day 14).
  • Luteal phase: from the day after ovulation to the day before the next period.
• Hormones:
  • Estrogen: produced by FSH, thickens the endometrium (uterine lining).
  • Luteinizing Hormone (LH): released when estrogen peaks, triggers ovulation.
  • Progesterone: produced by corpus luteum, prepares the uterus for a fertilized egg.

Evolution

• Evidence:
  • Fossil record: provides direct evidence for evolution, shows variation in time.
  • Comparative anatomy: homologous and analogous structures, vestigial structures.
  • Embryology: ontogeny summarizes phylogeny.
• Theories:
  • Jean Baptiste de Lamarck: proposed that organisms change over time in response to their environment.
  • Theory of Need: organisms change in response to changes in their environment.
  • Theory of Use and Disuse: organs that are not used will disappear, while those that are constantly used will develop.
  • Theory of Acquired Characteristics: organisms can pass on characteristics they acquire through use or disuse.

Proteins

• Characteristics:
  • Made up of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfur.
  • Polymers of amino acids, arranged in a chain called polypeptide.
  • Classified into primary, secondary, tertiary, and quaternary levels.
• Functions:
  • Help form many structural features of the body.
  • Act as catalysts, enabling cells to carry out chemical reactions.
  • Maintain proper concentration of ions and molecules for cells to function normally.

Lipids

• Characteristics:
  • Composed primarily of carbon, hydrogen, oxygen, phosphorus, and sulfur.
  • Hydrophobic nature dictates many of their uses in biological systems.
• Types:
  • Fats: a good source of stored energy.
  • Oils: used to form protective layers on the skin, preventing infection.
  • Waxes: used to form protective layers on the skin, preventing infection.
  • Steroid hormones: implicated in cancers of the female reproductive system.

Nucleic Acids

• Characteristics:
  • Capable of being broken down to yield phosphoric acid, sugars, and a mixture of organic bases (purines and pyrimidines).
  • Naturally occurring chemical compounds.