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PIRA Class: 6A02.35
Purpose:
To observe the straight-line propagation of light.
Description:
Set up a He-Ne laser pointer or laboratory laser to shine into a (very weak) solution of milky water or a cloud of chalk dust.
- Before creating chalk dust cloud (generated by slapping two "dirty" erasers together), be aware that some students may be asthmatic. Make sure cloud is not too large to affect even the front row.
- The chalk cloud is very effective (pedagogically), if you extend its scope all the way across the front of the classroom.
NOTE: Make sure that beam is not directed toward any space in the room that students might walk into, e.g. do not direct beam onto a door, above students heads, etc.
Pedagogy:
- Before generating the chalk cloud, ask student if there is light between the laser itself and the red spot that they see on the opposite wall.
- Ask students why they are able to see the laser beam with the chalk dust.
Equipment:
Laser, two dirty erasers or a weak solution of milky water in a large rectangular flask
Location:
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