BENDING LIGHT – DIFFRACTION

DOBLANDO LA LUZ – DIFRACCIÓN

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.

MATERIALS:

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

Activity 2: Laser pointer, narrow “slit” made in painted glass slide or aluminum foil with a single edge razor or craft knife (see specific instructions), spring-type clothespins as needed to hold everything in place

Activity 3: Two pencils

Activity 4: Laser pointer, tape, a hair at least 3 cm long, spring-type clothespins to hole everything in place, ruler, calculator. This activity requires calculations (unless you just want to look at the fringe pattern)

All these activities are done in a darkened room. Be sure to talk about laser safety first (keep lasers on the table when on, no waving beams around the room).

STUDENT INSTRUCTIONS AND TEACHER NOTES