Science - Waves Exam Notes

Waves

  • Transverse waves: up and down motion.
  • Longitudinal waves: back and forth motion.
  • Wave Parts: crest, amplitude, wavelength, trough, frequency, period.
  • Sound is longitudinal. Particles vibrate back and forth in the same direction as the traveling wave.
  • Compressions and rarefactions in longitudinal waves.
  • High frequency = High pitch; Low frequency = Low pitch.
  • High amplitude = Loud; Low amplitude = Quiet.
  • Sound needs a medium (media) to travel through.
  • Sound travels faster in water than air.
  • Sound waves can reflect, creating an echo.
  • Echolocation: bat/whale communication.

Thermal Energy Transfer

  • Conduction
  • Convection
  • Radiation
  • Insulators keep things cool/hot.

Light Waves

  • Light waves are transverse waves.
  • Travel in rays.

Human Eye

  • Structures: iris, pupil, sclera, retina, lens, ciliary muscles and ligaments, cornea, vitreous humor, aqueous humor, optic nerve, blind spot.
  • Light Path: Cornea -> aqueous humor -> pupil -> Lens -> vitreous humor -> retina.
  • Image is inverted; the brain interprets it.
  • Retina contains rods and cones.

Materials and Light

  • Transparent: light is transmitted.
  • Translucent: light is reflected.
  • Opaque: light is absorbed.

Luminosity

  • Luminous objects: emit light.
  • Non-luminous objects: do not emit light.

Law of Reflection

  • Angle of incidence = Angle of reflection.
  • Components: normal, incident ray, reflected ray, angle of incidence, angle of reflection, mirror.
  • Real vs. virtual images.

Refraction

  • Bending of light when it passes from one medium to another.
  • Denser medium: bends towards the normal.
  • Less dense medium: bends away from the normal.
  • Refractive index: how easily light travels through a substance.
  • Dispersion: White light through a prism separates into colors (ROYGBIV).
  • Short wavelengths (violet) refract more than longer (red) wavelengths.

Lenses

  • Convex lenses: converge light.
  • Focal point and focal length.
  • Concave lenses: spread out light.
  • Focal point and focal length.

Mirrors

  • Concave mirror: converging rays -> inverted enlarged reflection.
  • Convex mirrors: smaller image, larger area.

Colour

  • Color is determined by reflected wavelengths.
  • White: reflects all colors.
  • Black: absorbs all colors.
  • Primary colors: red, green, blue (all mixed together make white).
  • Secondary colors: cyan (green+blue), yellow (green and red), magenta (red+blue).
  • Colored filters absorb certain wavelengths.