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THINGS YOU NEED TO KNOW For Regents Physics Exam
MODERN PHYSICSBE VERY COMFORTABLE WITH THE ELECTROMAGNETIC SPECTRUM, ENERGY LEVEL DIAGRAMS, AND
STANDARD MODEL sections from the Regents Reference Tables.
5.3a5.3b-
5.3c-
5.3d5.3e-
5.3f-
5.3g-
5.3h5.3I-
5.3j
States of matter and energy are restricted to discrete values, not continuous values
QUANTIZED means “countable number”
(Bookcase Shelves, not a Ramp)
All charges are multiples of an elementary charge (1e = 1.6 x10 -19 C)
Electron charge = -1e, Proton charge = +1e
Conversion from 1e to coulombs is on RRT
Quarks have charges that are either +2/3e or –1/3e (see RRT)
KNOW THE PROCESS for getting from ELD to EMS and back.
A PHOTON is a discrete “package” of light energy.
Photons can be emitted or absorbed by electron dropping or jumping energy levels.
CONTINUOUS SPECTRUM-A smooth spectrum of all colors of the rainbow. Generated by light bulb
ABSORPTION SPECTRUM-looks like continuous spectrum with some spectral lines absorbed
By a cool gas
EMISSION SPECTRUM-a spectrum made up of only a few spectral lines emitted by an excited gas.
Energy of photon is proportional to frequency, and inverse to wavelength. E = hf c=f
At atomic level all things can exhibit both waves and particles characteristics. (wave-particle duality)
Wave characteristics-interference, refraction, reflection, diffraction
Particle characteristics-Collisions, reflection, momentum
ELECTRONS can collide with PHOTONS. Their combined momentums and energies are conserved.
If Electron losses energy, thus losses speed If photon losses energy, its frequency decreases
Because photon is light and must travel at c.
The sum of all mass + energy is conserved in the universe.
The sum of all charge is conserved in the universe.
Conservation means all BEFORE = all AFTER
Know the RRT Standard Model section
Protons are baryons made of u-u-d quarks
Neutrons are baryons made of u-d-d quarks
All quarks and leptons have antiparticle counterparts. All things the same except opposite charge.
All events and characteristics in the universe can be explained by the fundamental quarks and leptons
and the force interactions between them.
The Four Fundamental Force of the Universe (Strongest to weakest)
Strong (Nuclear) Force-Holds Protons and Neutrons (Nucleons) in the Nucleus of the atom.
Electromagnetic Force-Interactions of all charged particles. (Chemistry)
Weak (Nuclear Force)-Force behind radioactive decay.
Gravity-Extremely weak force at atomic level that attracts all mass to each other.
Gravity only appears strong on a large (planetary to galactic) scale
Because of it accumulative effect.
The Fundamental source of all energy is from the conversion of mass. (E = mc²)
A result of this is that the total amount of mass in the universe is constantly decreasing.
WATCH FOR THE PHRASE “MASS EQUIVALENT” OR “ENERGY EQUIVALENT”. Use E=mc².
It has been on most tests and many people miss this easy question.