Transcript Slide 1

_______________physics
1. Matter is a____________________
2. Light is a _________________.
This is "everyday" physics that deals with objects
that are relatively
1. _____________  bigger than _____________
2. _____________  v << _____
_______________ modified classical physics so that
it would give more accurate results when speeds
_______________________________ and for________________.
His theories are called the ________________ and
________________ Theories of _________________________ .
_______________ physics modified physics to deal with
_________________________ on the scale of ___________ .
According to this theory:
1. Matter can act like a___________________________.
2. Light can act like a___________________________.
Ex: Light in the classical view acts like a ___________
whose _________________ determines its energy:
_______________
 more____________
Ex: The ___________________ effect showed that light
can act like a ______________________ .
color of
light
brightness
of light
how many electrons were ejected
from the zinc and with what KE
red
dim
no e-
red
bright
no e-
violet
dim
a few e- with lots of KE
violet
bright
lots of e- with lots of KE
Einstein _____________________________ for a paper that
explained the photoelectric effect by assuming light
acted like ______________. The higher its _______________
the greater the energy of the light particle. Bright light
consists of ___________ particles.
_______________ light:
________________light:
________________light:
________________light:
 1_______ energy particle
cannot eject an enone of these many
_______ energy particles
could eject an e 1_______ energy particle
can eject 1 eeach of these many
________ energy particles
could eject an e-
The ______________ (basic unit) of electromagnetic
energy (light) is called a _______________ .
It has no
mass, but carries ______________ and ________________ .
Its energy is given by:
Eph =
where
h=
=
Ex: What is the
relationship between
Eph and f?
Eph
f
What quantity does the slope of the line?
Ex: What is the relationship between Eph and l?
Start with the equation:
Substitute c in for v:
Solve for f:
Substitute in the equation for
Ex: What does the
graph of Eph vs. l
look like?
Eph
l
The greater the wavelength, the ___________ the energy.
Ex: Find the energy of a blue light photon in joules.
Convert the answer to electronvolts (eV).
See page 1 of ESRT:
1 eV = ________________ J
_____________ theory - ____________________ energy
is emitted from and absorbed by _______________
in _____________ amounts or ________________ .
( ______________ means "separate, individual pieces.")
Ex: _______________
of a photon
before:
atom
Ex: _____________
of a photon
before:
atom
after:
atom has
______ energy
after:
atom has
_______ energy
Ex The ____________Effect: X-rays scatter off electrons.
e- at rest  KE =____
before
collision:
after
collision:
_______
photon
e- ____________
The scattered
photon now has
_______ energy.
So its f is _______
and its l is
______________
Both _________________and ______________ are conserved.
In sum, light can act like a __________________ or like
a ____________ . Which one it acts like depends on
the situation. When light interacts with..
… __________ , it acts
… ___________ , it acts
like a _________________
like a __________________
Examples:
Examples:
1/ __________________
1/ __________________
2/ __________________
2/ __________________
3/ __________________
Even when it is described as a photon, we still
use __________ properties such as _______________
and _________________ to describe it.
Electron charge: In 1909, Millikan sprayed drops of
________ into an _______________ field E.
Fe =___
oil drop
Fg =_____
By suspending the oil drop then letting it fall,
he was able to discover that the oil drops always carried
an ___________________________ of the fundamental charge
= ______________________ (the ______________ of charge).
which is the charge on 1 _____________ or _____________ .
 Charge is __________________ .
Models of the atom:
I. _____________________: In 1897, discovered e-’s were
________ mass and ____________________ charged. Since
he also knew that atoms as a whole were ______________,
he developed the ______________________________ model:
One _________ :
negative eare the
____________
positive charge is ________________
distributed in a___________________
_____________________ : In 1909, he fired ___________
particles (positively charged ____________ nuclei) at thin
gold foil:
only 1 in 8000 were
scattered ____________
________ were not
scattered or were
scattered through
_____________ angles
His conclusion:
The ___________________________ mass is concentrated in
_________________________ at the atom's _____________ .
He called this the ________________ of the atom.
II. As a result of Rutherford's experiment, the
___________________ model was developed:
One atom:
______________charge
concentrated in the
_____________
The e-'s ___________ the nucleus similar to how
________________ orbit __________________ .
size of nucleus ~ ___________________ of
`
the diameter of atom
_____________________with the solar system model:
1. Circular orbital motion  q _________________
2. Accelerating q  ______________emitted from atom
3.
Energy radiated  orbits will _____________________
4.
All atoms should ___________________in a short time
5. As they collapse, the e- should______________________
and the atom should _____________________emit a higher
and higher ______________________ of light
6. This should produce a ____________________spectrum.
but _______________ spectra were observed.
III. The Bohr model for ___________________:
1. The 1 e- in H____________________ or __________
____________the nucleus. It __________ in a ___________.
2. The e- can only be found at ______________ (certain
specially allowed) distances, which are unfortunately
still called __________________ .
 Each orbital has a _____________ number,____ .
a/ The orbital _____________to the nucleus is called
the ____________________and has n = ____. It has the
______________ energy = ______________.
b/ The orbital furthest from the nucleus has
the ______________energy and has n =_____. The energy
of that orbital = ____. In that case, the e- is said to be
_______________ , which means it is ________________
from the atom completely.
----- = _____________
A. Bohr model
of H atom:
_________
state of
electron
proton
n= 2 to ∞ are called
____________ states
The ______ ecan be found
at ______ level
etc…
 e- is___________
B. Photon _________________ :
If an e- moves from to a ___________ energy orbital to a
__________one, a photon of light is ___________ (given off).
photon
_________
The ____________ of the emitted photon: Eph =
Reference Tables: page 3, top left.
Ei =
Ef =
Eph = Ei – Ef
Eph =
Eph =
=
=
Easy way: IGNORE
NEG. SIGNS AND JUST
SUBTRACT!!!
C. Photon _________________ :
If an e- moves from to a ___________ energy orbital to a
__________one, a photon of light is ___________ (taken in).
photon
_________
The __________ of the absorbed photon: Eph =
Ef =
Eph = Ei – Ef
Eph =
Eph =
(ignore neg. signs)
=
Ei =
D. Energy ____________________:
Emission (the ____________of light):
Atom __________ energy
as e- moves __________
photon
___________
___________
atom
Absorption (the ____________ of light):
photon
__________
__________
Atom _________energy
atom
as e- moves_________
In both cases: _________________ = ___________________
E. NOTES:
1. The technical term for “jumps” is____________________.
2. No _______________________ jumps are allowed!!!
 Only jumps from one ______________energy level or
orbit to another ____________ energy level are allowed.
3. That is why _______________________ energy photons
can be emitted or absorbed by atoms..
4. Since Eph = hf, only certain __________________(colors)
are produced.
5. That is why photon energies
are ___________________(only
certain values are allowed).
Eph = Ei – Ef = hf
ΔE = amount of e-____________
Bigger e- jumps
(transitions)




more _________
more _________
_____________ frequency photons
in ___________________ and beyond
Little e- jumps
(transitions)




less _________
less _________
_____________ frequency photons
in ____________________ and lower
This is true for _______________ and _______________ .
_______
transitions
_______
transitions
involve
involve
_______
energy
light
_______
energy
light
Which transitions involve visible light?
F. ________________ : Jumps from any level to n = ___ will
___________the e- from the atom.
Ionization _________________:
The _____________required to
___________an e- from an atom.
What is the ionization
potential for a H atom that
has an electron in the ground
state?
What is the ionization
potential for a H atom that
has an electron in the n=3
state?
G. So where do _________________ (bright line) and
_____________________spectra come from?
Unless the source
is a low-density gas,
interactions with other
atoms blur the lines
into a _________________
spectrum.
The heated gas emits
absorbs, then emits
only those photons
from _____________
energy transitions.
The missing colors
are the __________ ones
that were_____________
by the gas.
V. Bohr’s model could NOT explain why e- could only
have ______________orbitals and energies. This was later
explained by_________________________:
The e- acts like a __________ and __________________
interferes with ___________ as it wraps itself around the
________________:
orbits
 This can only occur at certain ______________
distances from the nucleus.
VI. The ___________Model:
1. The electron is described by a ________ function, y.”
2. The square: y2 is the ___________________ of finding
an electron at a certain position. The e- is most likely to
be found where the "probability cloud" is ________________
3. The electron is no longer thought to be located at
a ________________ location, but may be ______________ .
4. The locations of highest probability correspond
to the positions of the old________________________.
_________
orbitals:
_________
clouds
Compare the 2 forces:
1. electromagnetic: Fe =
•
Is a force between two ___________________.
• Attracts ________________ and repels _____________
•
___________________  ________range
•
Binds the ____ to the ___ within an atom
and bonds_____________ to other ____________
2. strong nuclear: Fsn
•
Is a force between two _________________
•
Always________________, even between_____________
• _______________ force, but very ______________range
•
Holds the ____________________together
Ex: In a ____________
n =_____________
nucleus (___________):
p =___________
A close up of the 2 p:
Fsn ________________ > Fe ___________________
The _________________ wins  _____________nucleus
In addition, the ________________are also attracted
to the _______________ and to ________________ by the Fsn,
and they have ________ Fe repulsion.
Ex: In a ____________
nucleus (___________):
1
2
A close up of
protons 1 and 2:
1
2
The _______________ Fe is ______ the Fe in small nuclei.
BUT ______________Fsn is _____ the Fsn in small nuclei.
____________wins  nucleus __________ and _________
For bigger nuclei: # of n _____ # of p. Why?
The n’s provide extra Fsn _____________w/o Fe ___________.
The existence of the ______________force means that
there is an energy _____________ the nucleus called the
_______________ energy. __________________discovered that
this energy results in nuclei having more ____________ :
The _______________________ of Mass and Energy
Ex. If 5.0 x 10-3 kg of mass is totally converted
to energy, how much energy will result?
Notes:
1. If any object with ____________is converted completely
into pure ____________ , it will release a total of ________
joules. Think of mass as _________________ energy.
2. The term _______ is simply a ______________________
between mass m and energy E.
The mass is not
moving at the ________________________ !
3. What will the graph
E
shown at right look like?
What quantity does the
slope represent?
m
Ex 1:
____________
 splitting __________ nuclei into______________ ones
 used in __________________________
after:
before:
n10
Ba14256 + Kr9136 + 3n10
+ U23592
mass:
=
charge:
=
Is charge conserved?
Is mass conserved?
YES: The # of nucleons (n and p) is __________________.
NO:
The nucleons in Ba and Kr are ________________!!!
n10
+
U23592
Ba14256 + Kr9136 + 3n1o
_________mass!
____________mass!
The “missing” mass became _____________ ( E = mc2)
in the form of _______ of Ba, Kr, n and _________________.
This energy can be used 1/ _____________________________
in a ____________________ or 2/ ________________________
in an _______________________ .
Chain reaction - _______________________________________
_______________________________________________________
________________–
used to ____________the
reaction by ____________neutrons
Ex 2: _____________:
 combining ____________nuclei into _____________ ones
 powers _________________ and__________________
after:
before:
H21
+
He32 + n10
H21
mass
=
charge
=
Is charge conserved?
Is mass conserved?
YES: The # of nucleons (n and p) is __________________.
NO:
The nucleons in He32 and n10 are ________________!!!
H21
+
H21
_________mass!
He32 + n10
____________mass!
The “missing” mass became _____________ ( E = mc2)
in the form of _______ of He and n and _________________.
The # of fusion power plants = ____ because it is difficult
to get the _______________ close enough so that the
_________________ attraction > electric _________________ .
3. _________ production: a gamma ray _____________ gets
“tickled” as it passes a nucleus. Its ____________
becomes a _____________ and _________________ pair
after:
before:
g-ray
nucleus
nucleus
+
The nucleus acts like a _________________ .
The e+ is a _______________: the antiparticle of the e same ____________ as the e opposite ____________of the e-
a. Compare the charge q before and after:
=
+
 charge _______________________ .
b. Compare the mass before and after:
=
=
+
 mass _______________________ .
c. Compare "mass-energy" before and after:
=
+
mass-energy _______________________ as long as
Eph has an energy at least equal to _________________
Ex. Calculate the energy of the photon that is needed
to produce an electron and positron pair.
What is the frequency of the photon?
________________________ is ALWAYS conserved,
even when _______________ is not. This is because mass
can be converted to ________________ and vice versa, but
neither __________nor ____________ can be destroyed.
Ex: Is momentum p conserved?
after:
before:
Rewrite these as:
=
Momentum p is _____________________________ .
Ex:
Could a g-ray produce two electrons?
g
charge:
?
=
e-
e-
+
+
 _________________ b/c charge _____________conserved.
In sum:
1. Momentum is _____________________ conserved.
2. Charge is _________________________ conserved.
3. Mass is ___________________________ conserved.
4. Energy is _________________________ conserved.
5. Mass-energy is ____________________ conserved.
 Numbers ___ and ___ are ___________ conserved
when _______________ objects are involved.
4. Pair ______________________: matter and antimatter
combine to form pure _________________ (photons).
after:
before:
+
a. Compare the charge q before and after:
+
=
+
 charge _______________________ .
b. Compare the mass before and after:
+
=
=
+
 mass _______________________ .
c. Compare "mass-energy" before and after:
+
=
+
=
mass-energy _______________________ as long as
Eph has an energy at least equal to ____________
The idea behind particle accelerators (atom_____________):
________ particles
+ high __________:
_______
particles
because
________
The more the ________________ given to the old particles,
the more _________________ of the new ones by E = ______.
Ex: Early particle accelerators
used _______________ generators:
high _______________
work done on
a charge q:
W=
Ex: How much KE will a proton gain when it is
accelerated through a potential difference of 300,000 V?
W=
W=
W=
Ex: An example of a modern particle accelerator is
the_____________________ .
The _______________ field accelerates the particle.
The ______________ field is ____________________ to v, so it
only causes the particle to ___________________________ .
As accelerators with higher and higher
_____________ were built, particles with bigger and
bigger ____________were discovered.
There seemed to be no _____________
to the________________ of newly
discovered particles.
_____________________
_____________________
Finally, the _________________________ was worked out in
the _______________ . It explained how all particles with
mass are made up of ________________ fundamental
particles and their _________________________ .
The Standard Model: All matter (or antimatter) is
made up of ___________or combinations of____________.
_______
_______
__________________
increasing____________________
Neutrinos
have _______
_____ mass.
• Lepton means________________________
• Leptons all have charge _______or__________________
• Their antiparticles are charged __________________
• They occur____________________—they do not
___________________________________________.
increasing __________________
• Quarks all have charge _________or ___________
• Their antiparticles are charged _________ or_________
• They ___________________by themselves because you
cannot have a particle with a_________________________.
• They occur in groups of _____________________
particles
made from
___________
“bary-”
means
_______
masses
Must be all
__________ or
all_____________
“mes-”
means
_________
masses
Ex. A certain particle is made up of
3 quarks: 2 ________ quarks and
1 _____________ quark.
What is the total charge of the particle?
u:
Add up the charges:
u:
d:
Is this a baryon, a meson or a lepton?
This particle is also known as a________________
Ex. A certain particle is made up of 2
quarks: 1 ____ quark and 1 __________
quark.
What is the total charge of the particle?
Add up the charges:
u:
d:
Is this a baryon, a meson or a lepton?
This particle is also known as a ______________________
Ex. A certain particle is made up of
3 quarks: 1 _____ quark and 2 ________
d
d u
quarks.
What is the total charge of the particle?
u:
Add up the charges:
d:
d:
Is this a baryon, a meson or a lepton?
This particle is also known as a_____________________
Ex. A certain particle is made up of
u
3 quarks: 2 ________________ quarks
and 1 _________________ quark.
u
d
What is the total charge of the particle?
u:
Add up the charges:
u:
d:
Compare this one:
u
u
d
to:
u
u
d
The left-hand particle is an _______________________ . It is
an example of ___________________ . It has the __________
mass as the proton, but the _________________ charge.
Determine the charge and type of each particle.
quark content
s
d
total
charge
name
u
d
s
b
b
u
d
s
d
d
u
u
type
s
The total charge must be ____________________________
The Fundamental __________________ of Nature:
force
strong
nuclear
electromagnetic
weak
gravitational
range
relative
strength
what it
controls
Ex: How can gravity hold Earth to the Sun if it is the
weakest force?
1. Earth and Sun have a lot of ______________
2. Earth and Sun are _________________ , so the
__________________________ force is not important.
1. Earth and Sun are_______________ , so the
________________________ forces are not important.
Ex: The total amount of mass-energy in the universe
is:
ordinary matter: ______% (baryons and leptons)
dark matter: ______% (unknown)
dark energy: ______% (unknown)
Conservation Laws:
Total before =________________
1. _____________________ is always conserved.
=
2. In the absence of_______________ , ________________
is always conserved.
=
3. In the absence of________________, ________________
is always conserved.
Classical physics:
=
=
Modern physics:
=