PHYS 210L Lab Spectrometer, Fall 2014

PHYS 210 L The Spectrometer I. DIFFRACTON GRATING: A. Incandescent lamp: Illuminate the slit a) Describe the spectrum after looking at it. We see a continuous spectrum containing the whole range of visible colors from violet to red. Colors appear in the following order as we move the telescope from the initial position: Violet, Blue, Green, Yellow, Orange and Red. b) Angles measured in the first order: Extreme red: 23 degrees and 30 minutes. Extreme violet: 14 degrees and 42 minutes. c) Wavelengths: Using the formula d.sin = m. , with m=1, and d = (1/600) mm, we find the following:  Extreme red: 664.5818 nm Extreme violet: 422.9299 nm B. Mercury Lamp: a) Describe the spectrum you observe. What can you say about the mercury source? Through the telescope, we can observe the emission spectrum of the mercury: We find several colors distributed in a discontinuous way as strips in the following order: Violet, indigo, bluish green, phosphoric green, orange and red. b) Sharp line I II III IV V VI VII Angle (deg) Color Violet Indigo Bluish Green Phosphoric Green Orange Orange Red Wavelength (nm) 404.614 446.332 501.639 557.259 590.938 596.375 638.701 II. Prism: Mercury spectrum Number of orders per color: 1 The most deviated color: Violet. Minimum Deviation: Color () Violet Indigo Bluish Green Phosphoric Green Orange Red Angle n() 1.543 1.538 1.532 1.528 1.526 1.526 Plot n() versus . n v/s Wavelength y = -8E-05x + 1.5723 R2 = 0.938 1.52 1.525 1.53 1.535 1.54 1.545 0 100 200 300 400 500 600 700 Wavelength n