Atomic Fine Structure
In this experiment you will observe Hg and Na spectra using a precision spectroscope. The
accuracy of the measurements should allow you to observe and quantitatively analyze ne structure
in the Na atom due to the spinorbit interactio
Error Propagation-Part 2
Graphical error analysis
In some cases, the quantity to be estimated enters
a linear relationship (y = ax +b) between measured
quantities. Examples:
sin = (1/d) where d is to be estimated
Vs = (h/e) f /e where h and are to be
es
Formulas
x=
1
N
N
xi
1
N
=
i=1
N
(xi x)2
i=1
m =
N
f
x
A = f (x, y, z, .) A =
N
x=
i=1
2
N
1
xi
/
2
2
i
i=1 i
2
f
y
2
x +
N
x =
i=1
[(yi (xi ) (axi + b)]2
2
i
i=1
a=
2
2
z +
1
2
i
1/
2 =
2
f
z
2
y +
N
a =
N
1
2
i
xi
2
i=1
N
x2
i
2
i=1 i
P (x; p, n)
Compton Scattering
Introduction
Compton scattering is the name which has been given to the scattering process
+X +X
where represents a photon and X represents an element of matter such as an electron, atom,
nucleus, etc. In the language of collisions, thi
Error Propagation-Part 1
Review
Nature of experimental errors
Random (statistical)
Systematic
Control of experimental errors
Understand the instrument
Employ good technique
Make multiple measurements (by different independent methods if possible) a
PH255 FinalFall 2014
Write your answers to the following questions in the booklet provided. Except for steps
involving purely numerical calculations, you must show your work to receive credit for correct
answers. Partial credit will be awarded in the case
Observation of Spectra
In this lab, you will use a digital spectrometer to observe and analyze light specta from
various sources.
See the LeClair Laboratory Manual for information on the setup and operation of the
spectrometer. Extreme care must be exerci
Homework Assignment 1
1. How can the statistical uncertainty in a measurement be estimated? How can the eects of random
uctuations on a measurement be reduced?
Answer: Make multiple measurements and evaluate the spread in the results. Typically the spread
Homework Assignment 3
In providing answers to the questions below, always explain how you arrived at your answer.
1. In the electron e/m experiment, the charge to mass ratio is measured by accelerating electrons through
a potential dierence Vacc and then
Muon Lifetime
Introduction
The muon, conventionally denoted by the Greek letter , is an unstable elementary particle.
Its rest mass is 105.7 MeV/c2 . Together with the electron and tau, it comprises the three known
charged leptons appearing in the Standar
Nature and Control of
Experimental Errors
Experiment
An experiment is comprised of the
apparatus, procedures, and analysis
carried out to measure some quantity of
interest.
An experiment can range from very
simple to very complex:
Simple: voltage measu
Homework Assignment 4
In providing answers to the questions below, always explain how you arrived at your answer.
1. In a photoelectric eect measurement, the observed stopping voltages are tabulated below:
wavelength (nm)
578
546
436
405
stopping voltage
Physics 255: Modern Physics Lab
Measurement of the Speed of Light
Introduction: This experiment represents a direct measurement of the speed of light by
dividing the distance traveled by the light by the time required for the trip. The beam
from a laser a
Millikan Oil Drop Experiment
In this experiment, you will clock the rise and fall of charged oil drops under the influence of
electric, gravitational, and viscous forces. The charge on each drop can be calculated from
the experimental data. Under the hypo
Electron Diffraction
The purpose of this lab is to observe the wave properties of electrons, verify the de Broglie relation, and
determine lattice spacings in graphite carbon.
Equipment:
The electron diffraction tube comprises a gun, which emits a narrow
Gamma Ray Attenuation
Introduction
Photons interact with matter in a variety of ways: Compton scattering, photoelectric eect, pair
production, and Rayleigh (elastic) scattering. These interactions reduce the energy and/or change
the direction of the photo
The Photoelectric Effect
Introduction: In 1901 Planck published his quantum theory of radiation in which he stated that oscillators have a
discrete set of energy levels, and that energy levels between these discrete states never occur. He also stated that
Photon Detec*on
Mo*va*on
Photons are emi2ed or absorbed in transi*ons
between atomic and nuclear states.
Atomic transi*ons: change in energy of electrons
~1 eV (op*cal) to 10s of keV (X-rays)
Nuclear transi*ons: c
Homework Assignment 4
In providing answers to the questions below, always explain how you arrived at your answer.
1. In a photoelectric eect measurement, the observed stopping voltages are tabulated below:
wavelength (nm)
578
546
436
405
stopping voltage