By Ben Khabib

BY BEN KHABIB HOW TO USE A SPECTROSCOPE: DIFRACTION GRATING Note: This document was created based on the data my group has collected, while viewing normal light. • The “Using a Spectroscope” experiment is designed to show you how to measure the length of light waves. • When you direct a spectroscope at a light source you get the following image:

• A wide-spread question would be: “What is that rainbow square with numbers means?” A correct answer would be: Diffraction grating •

Diffraction grating splits or “diffracts” the light ray into the spectrum, while the numbers 4-7 mean the hundreds of nanometres. Indigo usually appears at around 4-4.5 (which means 400-450 nanometres) when normal light ray is viewed, while red appears at around 6-7, which means 600700 nanometres. Blue, green & yellow are in the middle & based on my group’s data; yellow has a wavelength of 600 nm, green: 530-600nm & blue has a wavelength of 450-500 nm.

• All of these measurements show the wavelengths of different colours of the spectrum, while viewing normal light (e.g. a light bulb) using a PMHS microscope.