University of West Florida

Modern Lab

  Physics > Course Goals

List of Experiments

 

Bohr Atom:

Objective: To observe the visible spectrum of hydrogen and helium and verify the Bohr model of the hydrogen atom by determining the spectral line positions. This means that you will derive the theoretical equation (4-22) in Tipler and compare those to the experimental values found in your manual.

    Questions: (Make sure show all of your work by stating the starting equation(s), declare your find, list necesary knowns unless already stated in paper, solve symbollically, and state numeric answer(s) with units. )
  1. What is the speed of the electron in the ground state written as a percentage of the speed of light?
  2. Do the energy of the emitted photons increase or decrease as the number of nucleons increases for hydrogen-like atoms? You should be able to reference the equation used in your answer from your paper.

e/m

Objective: Study the effects of electric and magnetic fields on a charged particle and measure the charge-to-mass ratio (e/m) of the electron.

Questions:

  • Why do we see the electron beam at all?
  • Suppose that protons were emitted in the vacuum tube instead of electrons. How would this effect the experiment?
  • Show that if the magnetic field is held constant, the time t required for an electron to make a complete circle in your e/m tube and return to the anode is independent of the accelerating voltage by deriving an expression for this time. The reciprocal f =1/t is called the electron’s cyclotron frequency.
  • Would a relativistic correction for the electron’s momentum be appreciable for the present experiment?

Millikan Oil Drop:

Objective: To determine the charge of an electron.

Note: You must fill out a form before you can access the system in the laser lab

Useful links:

Questions:

  • Use your results from e/m and Millikan Oil Drop to determine the mass of the electron. Don't forget to propagate your error.
  • Does this experiment allow you to determine if the charge of an electron is positive or negative? Explain.
  • Make sure to include the derivation for finding the charge starting from Newton's 2nd Law.

 

Michelson Interferometry

Objectives: (1) Calibrate the interferometer using a HeNe laser, (2) Measure the average wavelength of the Sodium doublet and the wavelength separation between doublet peaks.

Useful links:

AC Circuit Analysis

Objectives: (1) Build a high-pass/low-pass RC filter and measure the cross-over frequency, (2) Build an RC circuit and measure the RC time constant, and (3) Build and RLC circuit and determine the resonant frequency. All three should be compared to their theoretical values.

    Questions

 

  • RC Circuit: You must include the derivation for the amount of charge on the capacitor as a function of time and use it to find the time constant.
  • RLC Circuit: You must include the derivation for the resonant frequency as well as a phasor diagram.

Frank-Hertz Photoelectric Effect (Being repaired)

  • PhET simulation - link
  • Describe the effect of changing the intensity (amount) of light has on the current and stopping potential.
  • Describe the effect that different colors of light had on the stopping potential and thus on the maximum energy of the photoelectrons.
  • Defend whether this experiment supports a wave or a quantum/photon model of light based on your lab results.
  • Explain why there is a slight drop in the measured stopping potential as the light intensity is decreased.
  • Graphically determine the value for Planck’s constant h.
  • What is the work function of the photodiode tube

 

Finding Planck's Constant using and LED

    Questions:
  • The resistor in series with the LED is there for several very important reasons. List and explain at least 2 of them?
  • Interpret the intercept of your graph.

X-ray Diffraction (manual)

Objective: Determine the lattice spacing of crystals using the Tel-x-ometer and to become familiar with Rigaku Powder XRD.

Cloud Chamber w/decay series

(Note: You will need to take a cooler to the Chemistry Department to obtain dry ice.)

Objectives: (1) Observe and record the alpha emission (2) make a graph of mass number (y-axis) vs. atomic number (x-axis) for each element in the series. Write the element’s symbol at its point on the graph and connect the appropriate points in order of decay with an arrow.

Gamma-Ray Spectroscopy

Objective: To record the spectra of several materials, identify each peak, and compare your data to the theory.

Note: You must describe the decay process of each material and present the energy diagrams with transitions shown.

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