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Flashcards in Physics Basics Deck (64)
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1

What is the term to describe two atoms whose nuclei contain the same number of protons but different numbers of neutrons?

Isotopes

2

What is the term to describe two atoms whose nuclei contain the same number of neutrons but different numbers of protons?

Isotones

3

What is the term to describe two atoms whose nuclei contain the same number of nucleons but differ in their nuclear energy states?

Isomers

4

What is the mass of an amu (atomic mass unit)?

1/12 the mass of a C-12 atom = 1.66x10-27 "in between" weight of proton/neutron

5

What is an electron volt (eV)?

The kinetic energy acquired by an electron passing through a potential difference of 1V

6

What is the energy equivalent (E0) [E=mc2] of an electron at rest?

E0 = 0.511 MeV

7

What is the energy equivalent [E=mc2] of 1 amu?

931.5 MeV

8

Electrons can exist only in those orbits for which the angular momentum of the electron is an integral multiple of ____.

h/2π (h = Planck's constant = 6.626x10-34 J-sec)

9

What is the maximum number of electrons in an orbit?

2(n2)

10

What are valence electrons?

Electrons in the outermost shell (lowest binding energy)

11

What impact does the Z of an atom have on the Coulomb forces/binding energy of electrons?

Higher Z = higher binding energy due to greater nuclear charge

12

What are the four fundamental forces of nature, in order of strength?

  • Strong nuclear force (strongest)
  • Electromagnetic force
  • Weak nuclear force
  • Gravity

13

What equation describes the amount of energy carried in a photon?

E = hv (h = Planck's constant = 6.626x10-34 J-sec)

14

As the wavelength of a photon becomes shorter, what happens to frequency? Energy?

As wavelength shortens...

  • Frequency - higher
  • Energy - higher

15

What is the A of an atom (i.e. I-131)? What is the Z of an atom?

A = mass number = number of nucleons Z = atomic number = number of protons **In a stable nucleus, A should = 2*(Z)

16

What is the Half Value Layer (HVL)? What equation describes this?

HVL = amount of material required to attenuate beam to 1/2(E0) HVL = [-ln(0.5)/u] where u(mu) is a constant of the material

17

What is pair production? What is the threshold energy of the incident photon required for pair production to occur?

Pair production = photon passes close to nucleus, resulting in energy conversion into positron-electron pair Threshold energy = >/=1.022 MeV

18

What is the energy dissipated by an ionizing event?

~33eV

19

What is the difference between x-rays and gamma-rays?

x-rays produced extranuclearly, g-rays produced intranuclearly **otherwise identical in nature and properties

20

Where to x- and game-rays fall on the electromagnetic spectrum?

Short-wavelength end

21

What are alpha particles?

Nuclei of helium atoms consisting of two protons and two neutrons with a net positive charge Can be produced by an accelerator or by decay of heavy nucleotides (i.e. uranium, radium)

22

Which sources of radiation are directly ionizing? Indirectly ionizing?

charged particles - directly ionizing (sufficient kinetic energy to disrupt atomic structure of absorber) electromagnetic radiation - indirectly ionizing (when absorbed, give up energy produce fast-moving charged particles that produce damage)

23

What is the Compton process?

Incident photon strikes outer shell electron, ejecting the electron (transfer of kinetic energy) and diverting the path of the now lower energy incident photon (scattering)

24

Following a Compton interaction, is the wavelength of the scattered photon higher or lower than that of the incident photon?

lower (lower energy)

25

An interaction proceeds as follows: an incident photon strikes an inner-shell electron, giving up all of its energy and resulting in ejection of the electron from its shell. What type interaction has just occurred?

Photoelectric effect

26

An interaction proceeds as follows: an incident photon strikes an inner-shell electron, giving up all of its energy (ie photoelectric effect) and resulting in ejection of the electron from its shell. What is the result of this ejection?

- Electron from an outer shell "drops down" to fill the vacancy - Emission of characteristic x-rays by this transfer of energy

27

The mass absorption coefficient for which of the following process varies based on Z: -Compton process -photoelectric effect

photoelectric effect

28

What is a free radical?

atom/molecule with an unpaired orbital electron in the outer shell

29

Which sources of radiation are directly ionizing? Indirectly ionizing?

charged particles - directly ionizing (sufficient kinetic energy to disrupt atomic structure of absorber) electromagnetic radiation - indirectly ionizing (when absorbed, give up energy produce fast-moving charged particles that produce damage)

30

What is the Compton process?

Incident photon strikes outer shell electron, ejecting the electron (transfer of kinetic energy) and diverting the path of the now lower energy incident photon (scattering)