BENDING LIGHT – DIFFRACTION

DOES LIGHT ALWAYS MAKE A SHARP SHADOW WHEN IT IS BLOCKED BY AN OBJECT? WHAT HAPPENS WHEN LASER LIGHT PASSES AROUND A THIN HAIR? CAN YOU USE THE PATTERN OF DARK AND BRIGHT SPOTS TO MEASURE THE DIAMETER OF THE HAIR?

 

The calculations in this lesson require that students understand and can manipulate numbers in scientific notation. The qualitative activities- looking at diffraction fringes- can be enjoyed by students of all ages.


All these activities are done in a darkened room. Be sure to use lasers with safety in mind!


MATERIALS (Details in teacher notes below)

Activity 1 – What Do You Expect to See?

  1. Laser pointer, sewing pin with a “ball” head, spring-type clothespins as needed to hold everything in place

Activity 2 – Shadow of a Thin Slit

  1. Laser pointer, narrow “slit” made in painted glass slide or aluminum foil with a single edge razor or craft knife, spring-type clothespins as needed to hold everything in place

Activity 3 – Do I Need a Laser?

  1. Two pencils

Activity 4 – Using Diffraction to Measure the Width of a Hair

  1. Laser pointer, tape, a hair, spring-type clothespins to hole everything in place, ruler, calculator. This activity requires calculations (unless you just want to look at the fringe pattern)



STUDENT INSTRUCTIONS AND TEACHER NOTES


Bending_Light-Diffraction_Slides.pptx.zip  (PowerPoint slides with student instructions)


Difracción.PPT.zip  (Presentaciones de PowerPoint con instruacciones para estudiantes)


Bending Light-Diffraction_Teacher_Notes.pdf


Bending_Light-Diffraction_Observations.pdf  (Student data and observations)


VIDEO: Viewing the Diffraction Pattern of a Pin at Home


VIDEO: Measuring Hair Diameter by Diffraction


VIDEO: Measuring Hair Diameter by Diffraction (version with  typical math errors)



Rev. 1/22/17