Untitled Flashcard Set
Term: When light slows down entering a new medium
Definition: It bends toward the normal.
Term: When light speeds up entering a new medium
Definition: It bends away from the normal.
Term: Law of reflection
Definition: Angle of incidence equals angle of reflection.
Term: Diffuse reflection
Definition: Scattering of light from a rough surface.
Term: Fermat’s Principle
Definition: Light takes the path of least time.
Term: Why the Sun appears higher at sunrise/sunset
Definition: Atmospheric refraction bends sunlight.
Term: Why stars twinkle
Definition: Turbulent air refracts starlight unpredictably.
Term: Cause of a mirage
Definition: Total internal reflection in hot, less dense air.
Term: Total internal reflection
Definition: Occurs when angle > critical angle going dense → less dense.
Term: Index of refraction formula
Definition: n = c / v.
Term: Why the sky is blue
Definition: Short wavelengths scatter most.
Term: Why sunsets are red
Definition: Blue light scatters away over long paths; red survives.
Term: Why clouds are white
Definition: Water droplets scatter all visible wavelengths.
Term: Cause of a rainbow
Definition: Dispersion + internal reflection inside raindrops.
Term: Cause of thin film interference
Definition: Interference between reflections from top and bottom surfaces of a thin film.
Term: Why soap bubbles show colors
Definition: Thin film interference.
Term: What determines thin film colors
Definition: Film thickness and wavelength of light.
Term: Fluorescence
Definition: UV excites electrons which emit visible light.
Term: Why fluorescent lamps use phosphor
Definition: Converts UV light to visible light.
Term: Difference between fluorescence and phosphorescence
Definition: Phosphorescence emits light slowly due to metastable states.
Term: Emission spectrum
Definition: Bright lines emitted by excited atoms.
Term: Absorption spectrum
Definition: Dark lines where atoms absorb specific wavelengths.
Term: Alpha radiation
Definition: Helium nucleus (2 protons, 2 neutrons).
Term: Alpha decay changes
Definition: Atomic number –2, mass number –4.
Term: Beta minus decay changes
Definition: Atomic number +1, mass number unchanged.
Term: Gamma emission changes
Definition: No change in atomic or mass number.
Term: Highest penetrating radiation
Definition: Gamma radiation.
Term: Strong nuclear force
Definition: Short-range but strongest force; binds nucleons.
Term: Why large nuclei are unstable
Definition: Strong force weakens at long distances; proton repulsion increases.
Term: Free neutron behavior
Definition: Beta decays into proton, electron, and antineutrino.
Term: Radioactivity
Definition: Spontaneous decay of unstable nuclei.
Term: Half-life
Definition: Time for half the radioactive sample to decay.
Term: Radiation used in smoke detectors
Definition: Alpha radiation.
Term: Nuclear fission
Definition: Splitting a heavy nucleus into smaller ones with energy release.
Term: Main source of fission energy
Definition: Kinetic energy of fission fragments.
Term: Condition for chain reaction
Definition: Critical mass.
Term: Moderator function
Definition: Slows neutrons.
Term: Control rods function
Definition: Absorb neutrons.
Term: Coolant function
Definition: Transfers heat from the reactor core.
Term: Breeder reactor production
Definition: Converts U-238 into Pu-239.
Term: Nuclear fusion
Definition: Joining light nuclei into heavier nuclei with energy release.
Term: Fusion in the Sun
Definition: Hydrogen fuses into helium.
Term: Why fusion releases energy
Definition: Mass per nucleon decreases.
Term: What is conserved in fission and fusion
Definition: Number of nucleons.
Term: Fastest-moving radiation
Definition: Gamma.
Term: Scientist who explained nuclear fission
Definition: Lise Meitner.
Term: Mass–energy equivalence
Definition: E = mc².
Term: Photon energy equation
Definition: E = hf.
Term: Wave speed formula
Definition: v = fλ.
Term: Cause of absorption lines
Definition: Atoms absorb specific frequencies of light.