# lab40 - LAB 40 THE ATOMIC SPECTRUM OF HYDROGEN INTRODUCTION...

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LAB # 40: THE ATOMIC SPECTRUM OF HYDROGEN INTRODUCTION: Long before anyone understood what they were seeing, gratings were used to observe the spectrum of hydrogen. Several things were very puzzling. First, why were only certain discrete wavelengths (colors) of light emitted and not others? Second; Balmer had discovered that the wavelengths seemed to fit into very interesting patterns. They could be calculated by the simple formula: ! = B n 2 n 2 " 2 2 # \$ % ( Where n = an integer larger than 2 and B = an constant = 3645.6Å (1 Å = 10 -10 ). Before your lab period, calculate the wavelengths that the Balmer formula predicts for n= 3, 4, 5, 6, 7. How many of these correspond to visible light? Looking in your textbook could help with this question. APPARATUS : Hydrogen lamp, Hg bulb, Na bulb, Gratings, Single filament lamp, Meterstick, stand, PROCEDURE: Look through a grating at a hydrogen lamp. See Fig. 1. You should see at least three lines: red, blue-green and blue-violet. 80% of the people can see a fourth

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## This note was uploaded on 02/29/2012 for the course PHYS 227 taught by Professor Rabe during the Fall '08 term at Rutgers.

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lab40 - LAB 40 THE ATOMIC SPECTRUM OF HYDROGEN INTRODUCTION...

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