2. View the light source when covered with first a red filter and second a blue filter. Stand about 3.0 In from the light. You must be able to see the bands and the scale behind it. 3. Allow the laser to pass through the double slit and let the interference pattern be projected on a scrap of white paper. On the paper, mark the location of several adjacent bright spots using a pen. Number of bright bands used Span of interference pattern Average Ax Distance between slits 'd' Viewing distance S L! Calculated wavelength