51ºÚÁÏ

This practical lesson is designed to develop students’ understanding of diffraction gratings and the measurement of light wavelengths. Students will investigate how red, green, and blue light are diffracted and use their results to calculate wavelengths accurately.

The lesson includes:

Starter Activity: An engaging PowerPoint slide to recap prior knowledge about the wave nature of light and introduce diffraction gratings.

Lesson Description: A clear explanation of the aims of the experiment, highlighting the significance of measuring the wavelengths of different colours.

Method: A step-by-step guide detailing how to set up the diffraction grating, align the laser or ray box, measure the diffraction angles, and record the data.

Equipment List: Includes a laser (or ray box with coloured filters), diffraction grating, ruler, protractor, white screen, and mat for equipment placement.

Risk Assessment: Covers safe handling of lasers (avoiding direct eye contact), ensuring cables are neatly managed, and general laboratory safety.

Results Table: A structured table for recording angles of diffraction and calculated wavelengths for red, green, and blue light.

Comparison Table: Allows students to compare their calculated wavelengths with accepted values and evaluate the accuracy of their experiment.

Mat Layout: A printout showing the recommended positions for different pieces of equipment, helping to standardise the setup and improve accuracy.

Analysis: Guidance on using the diffraction grating formula to calculate wavelengths and discussion questions to encourage critical thinking about sources of error and reliability.

This practical can be carried out using either a laser (providing a more precise, monochromatic beam) or a ray box.

This lesson aims to build students’ confidence in experimental design, data analysis, and evaluation skills, preparing them for higher-level physics studies and reinforcing the wave nature of light.