Chapter 11: Modern Physics

Quanta

the origin of the name of quantum mechanics

Photon

is a quantum of electromagnetic energy

Photoelectric effect

is an illustration of light that behaves like a steam of photons

Photoelectrons

are the released electrons

Metal’s work function, ϕ

is a certain amount of energy had to be imparted to an electron on the metal surface in order to liberate it

Electronvolt (eV)

is equal to the energy gained (or lost) by an electron accelerated through a potential difference of one volt

In terms of electronvolts, the value of Planck’s constant is

Atomic Spectra

the produced patterns of sharp lines when the light from a glowing gas, passed through a prism to disperse the beam into its component wavelengths

Balmer formula

Electromagnetic radiation

propagates like a wave but exchanges energy like a particle

Wave function, Ψ

is the mathematical probability that a particle will be measured to be at a particular position when the position is measured

Theory of Relativity

a theory that have two postulates: (1) The results of physical experiments will be the same in any non-accelerating reference frames, and (2) The speed of light is constant.

Time dilation

is the difference in the elapsed time as measured by two clocks

Length contraction

a phenomenon in which moving along with the object, measures will observe the object to have a different length compared in a different reference frame

Nucleons

collectively are protons and neutrons

Atom’s atomic number

the number of protons in a given nucleus (denoted Z)

Neutron number

the number of neutrons in a given nucleus (denoted N)

Nucleon number

also called mass number is the total number of nucleons, Z + N (denoted A)

Isotopes

are nuclei that contain the same numbers of protons but different numbers of neutrons

Mass defect Δm

the difference between the mass of any bound nucleus and the sum of the masses of its constituent nucleons

Energy formula

Binding energy

of the nucleus formula tells how strongly the nucleus is bound:

Binding-energy-per-nucleon: