4d

Question 1

how light and sound interact with matter

Answer 1

• light is a form of electromagnetic radiation — waves of electric and magnetic fields that transmit energy
• behavior of light depends on its frequency
• particles of light are used in optical elements of the eye to focus rays of light on sensory elements
• when light interacts w matter, spectroscopic changes occur that can be used to identify the material on an atomic or molecular level
• differential absorption of electromagnetic radiation can be used to generate images useful in diagnostic medicine

-interferences and diffraction of light waves are used in many analytical techniques

• photon model of light explains why electromagnetic radiation of different wavelengths interact differently with matter
• oscillating pressure waves (“sound”) is generated when mechanical energy is transmitted through solids, liquids, and gases
  ~ sound waves are audible if the sensory elements of the ear vibrate in response to expose to these vibrations
  ~ detection is used in ultrasound imaging
  ++ noninvasive technique locates dense subcutaneous structures and useful in diagnostic medicine
• content:
  ~ properties of light
  ~ properties of sound
  ~ how energy waves interact with matter

Question 2

sound

phys

Answer 2

• production of sound
• relative speed of sound in solids, liquids, and gases
• intensity of sound, decibel units, log scale
• attenuation (dampening)
• doppler effect: moving sound source or observer, reflection of sound from a moving object
• pitch
• resonance in pipes and strings
• ultrasound
• shock waves

Question 3

light, electromagnetic radiation

phys

Answer 3

• concept of interference; young’s double slit experiment
• thin films, diffraction grating, single-slit diffraction
• other diffraction phenomena, x-ray diffraction
• polarization of light: linear and circular
• properties of electromagnetic radiation
  ~ velocity equals c in vacuo
  ~ electromagnetic radiation consists of perpendicularly oscillating electric and magnetic fields; direction of propagation is perpendicular to both
• classification of electromagnetic spectrum, photo energy E = hf
• visual spectrum, color

Question 4

molecular structure and absorption spectra

ochem

Answer 4

• infrared region
  ~ intramolecular vibrations and rotations
  ~ recognizing common characteristic group absorptions, fingerprint region
• visible region (gen chem)
  ~ absorption in visible region gives complementary color (carotene)
  ~ effect of structural changes of absorption (indicators)
• ultraviolet region
  ~ π-electron and nonbonding electron transition systems
  ~ conjugated systems
• NMR spectroscopy
  ~ protons in magnetic field; equivalent protons
  ~ spin-spin splitting

Question 5

geometrical optics

phys

Answer 5

• reflection from plane surface: angle of incidence equals angle of reflection
• refraction, refractive index n; snell’s law: n₁ x sin x₁ = n₂ x sin x₂
• dispersion, change of index of refraction with wavelength
• conditions for total internal reflection
• spherical mirrors
  ~ center of curvature
  ~ focal length
  ~ real and virtual images
• thin lenses
  ~ converging and diverging lenses
  ~ use of formula 1/p + 1/q = 1/f with sign conventions
  ~ lens strength, diopters
• combination of lenses
• lens aberration
• optical instruments, including human eye