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New Recommendations for the Safe Use of Laser Pointers

David Gervais, Chair STAO Safety Chair

STAO’s Safe on Science booklet is a great resource for teachers and is used as the standard for safe practices by many school boards in Ontario. It presently states that only class 1 and 2 lasers should be used in the classroom. This bans almost all laser pointers from your classroom. A recent OAPT Newsletter article questioned why class 3R lasers (most regular laser pointers) are not accepted. After carefully reviewing the literature and holding extensive discussions, STAO has decided that laser class 3R should be added for recommended use in schools. The Safe on Science booklet is being revised and will be completed by March 31. This will be sent to school boards in the province. Read More...

Pointers about Laser Safety

Roberta Tevlin, OAPT Newsletter Editor, Physics Teacher Danforth CTI
Roberta.tevlin@tdsb.on.ca

There is a lot of confusion about which lasers we can and should use in our classrooms. Lasers are classified by power, spread of beam and a variety of other properties. The lower the Class, the safer they are. Read More...

Wire Fire!

Joanne O’Meara, Department of Physics, University of Guelph
omeara@physics.uoguelph.ca

This demonstration is a nice way to illustrate the P = I 2R relationship that is discussed in electric circuits. Figure 1 illustrates the equipment: a Variac transformer takes the wall output of 120 V and generates a variable voltage from 0 to 140 V. This is then sent through a Hammond Manufacturing transformer (167X5), converting down to 5 V output. We use this second transformer in order to increase the current through the wires. The output from the second transformer is connected to three wires in series: approximately 10 cm in length of each of ~18 gauge Nichrome, steel and copper. A piece of folded paper is placed on each wire. Read More...
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