Chapter 33 Flashcards
Isotope
Different number of neutrons, same number of protons
Isotones
Same number of neutrons, different number of protons
Isobars
Same mass but different numbers of neutrons and protons
Atomic mass unit
1/12 of the mass of a C12 atom
Value of one meV is
The energy of one atomic mass unit, 931.5
Nucleon
Particle of the atomic nucleus, neutron or proton
Formula for radius of a nucleus
r=1.2fm * number of nucleons
All nuclei have the same density, T/F
True
Forces in a nuclei
Coulomb force (repulsion b/w protons)
Strong force/Nuclear force (attraction between protons and neutrons)
Weak force (acts between nuclei but doesn’t play role in binding)
Gravitational
Weird thing about strong force
Repulsive if nucleons get close enough, attractive before that point over another short range. Prevents nucleus from collapsing
Binding energy
Energy needed to separate nucleus into components
Calculate Binding Energy
BE= mass componentsc^2-mass nucleic^2
Can also do it per nucleon
Why is a binding energy curve the way it is
At small # of nucleons, not a lot of forces happening, but it increases the more nucleons you add. Past a certain point its too big for forces other than coulomb to act on all the molecules, so it starts binding less tightly again
Why can’t you just add neutrons forever
above a certain amount of neutrons they just turn into protons because magic?
alpha particle made of
Helium nucleus
Positron is the
antiparticle of an electron. Same mass different charge
Exponential decay law
N=N0 *e ^-lambda t
Decay rate equation and units
R(t) = lambda N(t) or R(t) = R0 *e^ -lambda t Units are becquerels (Bq) 1 Bq= 1 decay/s
Q value of a reaction
gain or loss of kinetic energy (used as bond energy) in the reaction
Q= Mi - Mf *c^2
Things conserved in a nuclear reaction
Charge Momentum Angular momentum Nucleons NOT MASS
decay diagrams axises
Energy on y
atomic number on x
compare daughter and parent
Beta decay
change charge by one unit
beta minus emits an electron
beta plus emits a positron
Gamma decay
lose energy
Isomers
differ in energy state
Excited energy state called
metastable state
When considering energy emmitted in fission, similar to decay except
also must consider energy of bombarding neutron
Absorbed dose versus equivalent dose
Amount of radiation you absorb from an exposure versus how much damage is caused to tissue (absorbed dose times radiation weighing factor)
Applications of Nuclear Physics
Bomb detectors
Smoke detectors
Triboelectric charging
rub to objects together, positive charge builds up on one, negative charge builds up on the other
Current is the
rate of flow of charges (amps)
Force of gravity equation
GMm/r^2
Electric force equation (Coulomb’s law)
F=kq1q2/r^2
How can we measure an electric field?
Put a test charge in it, measure the force on the charge, use E=F/q
We define E as force on a positive test charge
Linear charge density equation
u = Q/L
Charge on a linear element
Units of C/m
Electric field for continuous charge distribution equation
E= k * delta q/r^2
Surface charge equation
Q/A= surface charge
Potential Energy between charges equation
U = kQq/r
Electric potential of point charge
V=kQ/r
Way to find work required to move charge
Find difference in electric potentials intially and finally
multiply it by the charge being moved
Electric field lines are ______ to equipotential lines.
perpendicular
Equation for change in potential energy
delta U =q delta V
An electron volt is
energy change when one elementary charge moves through a potential difference of one volt
When a static charge is in a conductor…
there is no electric field component directed along the conductor
If you have a charge density question, what do you assume if its an insulator? A conductor?
Insulator you have to choose an assumption, usually that charge is evenly distributed but this doesn’t have to be so
With a conductor all the charge goes to the outer surface
We can consider electric flux as a measure of
How many electric field lines pass through a given area
Electric flux equation
Electric field times area
Guass’s Law
Electric flux through any closed surface is given by the enclosed charge within the region bounded by that surface divided by the permittivity of free space
E delta A = q/(epsilon naught)
Magnitude of charge from an infinite line equation
E= u/ (2pi r (epsilon naught))
Strength of an electric field of an infinite uniform plane of charge depends on distance from it. True/False
False. Constant at any distance
Potential inside a charged conducting shell is constant but not necessarily zero. True/False
True
When charges of the same sign are moved together it requires ________ ________ and the _____ ______ ______increases
Positive work
Electric Potential energy
