Physics Review Unit 10 Modern Physics | Concordia University Wisconsin

University:
Concordia University Wisconsin
Course:
PHYS 1524 | General Physics II
Academic year:

2019
Views:

277

Pages:

3
Author:

Trevon Bernard

Unit 10: Modern Physics Quantum Theory: Evidence proposed by Max Planck that supported that light has both wave and particle properties. The quantum theory theorizes that electromagnetic energy is both emitted and absorbed in packets. The packets that are emitted and absorbed are known as quantum. The quantum of electromagnetic energy is known as a photon. 1. Electromagnetic radiation is emitted from a bundle of light waves also known as photons. 2. Photons contain energy in regard to its frequency. Planck’s Constant: The unit (h) in which a photon’s energy can be related to its frequency. The Compton Effect - Arthur Compton carried out an experiment in which he was able to bounce an x-ray photon off an electric that created an electron with more kinetic energy that it previously had and an x-ray with less kinetic energy it previously had. A collision occurs allowing energy to be transferred to the electron. Both energy and momentum is conserved before and after the collision. - The Matter-Wave Theory - DeBroglie theorized that any particle of matter that has linear momentum is also considered a wave because if it has momentum, it has mass and velocity. Models of the Atom - Thomson’s Model: Thomson’s model proposes an atom that consists of a uniform distribution of positive and negative charges. - - Rutherford’s Model: Rutherford performed an experiment using gold foil, alpha particles, and a lead box with a small opening. Alpha particles that passed through the opening of the lead box were allowed to escape and follow the line to the gold foil. Most of the alpha particles were able to pass through the opening and only some of the alpha particles were deflected. Very few alpha particles bounced off the foil. Rutherford concluded that the atom is 99.99% empty space and the nucleus contains a positive charge and has the most mass in the atom. - The Bohr Model - Bohr’s model depicted electrons travelling in circular orbits around the nucleus. These electrons can jump from one orbit to another when in an excited state. Bohr’s model depicted Bohr’s belief that all forms of energy are quantized. Kinetic energy is only gained or lost in fixed quantities. - Each orbit in the atom had a specific amount of energy. The orbit closest to the nucleus has the least possible amount of energy for the electron. -