AS 101 – Lab Exercise 1 - Boston University



Pre-Lab

1. State and/or sketch Kirchoff’s Laws in your own words.

2. What is a diffraction grating and how will you use it?

3. What type of spectrum should we see from a gas discharge tube?

4. What causes a continuous spectrum, an absorption spectrum, and an emission spectrum?

5. What is a spectroscope and how will you use it?

Lab Report

3 Page Limit : Please Attach Your Data Pages

Introduction: State the goal of, and briefly describe the experiment you performed.

Equipment: List the pieces of equipment you used.

Emission Spectrum:

Continuous Spectrum:

Absorption Spectrum:

Procedure: Describe the steps of your experiment.

Emission Spectrum:

Continuous Spectrum:

Absorption Spectrum:

Results/Discussion:

Emission Spectrum (show all necessary work):

What was the resolution of your spectroscope?

Show the calculation of your calibration offset?

Did your spectroscope measure wavelengths to be redder or bluer than the true values?

Knowing that the energy, wavelength, and frequency of light are all relatable by physical constants, find all three for H alpha. Use units of Joules, Meters, and Hertz.

Why does the gas inside your emission tube produce H alpha photons?.

What was were the mystery emission gasses and how did you come to your answer?

Continuous Spectrum:

Describe any changes you observed in the light spectrum of the bulb as you changed the voltage. Relate these changes to the two laws of thermal radiation.

Describe any changes you observed in the light spectrum of the bulb as viewed through 3 different chemicals. Our atmosphere behaves in a similar way, blocking out entire bands of the EM spectrum.

Absorption Spectrum:

Describe some of the absorption features you observed.

By comparing the absorption features to the solar spectrum on the wall of the lab identify some of the elements in the solar atmosphere that caused absorption.

Compare your observed absorption lines in the solar spectrum to the emission spectrum from the sodium lamp.

What were the mystery chemicals and how did you arrive at your answer?

Fill out the chart for electrons falling from the different energy levels of Hydrogen. Were you able to see these emission lines?

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n = 2

n = 3

n = 4

n = 5

n = 6

n = 7

» = ________ E = ______

» = ________ E = ______

» = _______ E = _______

λ = ________ E = ______

λ = ________ E = ______

λ = _______ E = _______

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