Spectrophotometer Essay

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Objective To build a spectrophotometer and use it to investigate the absorption of visible light in differently colored solutions. When light hits an object, some of that light is absorbed by the object, and the light that is not absorbed is what we see. In this science project, we build a simple spectrophotometer from a cell phone and use it to investigate how visible light is absorbed by differently colored solutions. Materials: • A piece of wood at least 40 cm by 15 cm that can be taken into a room that can be made very dark • Metric ruler or measuring tape • A small, visible-light diffraction grating; a 500 lines/mm (12,700 lines/inch) linear grating is recommended. • Transparent adhesive tape • A small, white LED bulb. (5mm) Specifically • Battery, CR2032, 3V 20 mm coin. • Electrical tape • A small piece of wood or polystyrene, about 2 cm thick, or a baseplate template, large enough to place the light source on top of. • Cups (one for each food color you want to test) • Water • Graduated cylinder, 10 mL, or measuring spoons • Food colors, including blue, red, and yellow • Cuvette, 3.5 mL (at least 4). • Optional: Medicine dropper • Cell phone with camera • Pencil • A computer that can run Windows® software • Lab notebook Procedure: 1. In this part of the science project, you will assemble the cell phone spectrophotometer. You will need a hard, flat surface that can be used in a dark room, and on this surface you will position your diffraction grating and light source (the LED bulb) in such a way that you can see a line of colors, or spectrum, coming through the center of the diffraction grating. a. You will be assembling your spectrophotometer on a hard, flat surface in a room that can be made very dark. This could be a desk or dresser in the room, or a piece of wood (at least 40 centimeters [cm] by 15 cm) that can be taken into the

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