• If you are citizen of an European Union member nation, you may not use this service unless you are at least 16 years old.

  • Stop wasting time looking for files and revisions! Dokkio, a new product from the PBworks team, integrates and organizes your Drive, Dropbox, Box, Slack and Gmail files. Sign up for free.

View
 

Fall 2014 Phys 132 Reminders from 10-24 Training

Page history last edited by Kim Moore 5 years, 5 months ago

Reminders from TA/LA Training on 10/17/2014 for week of 10/20 (Lab 9, Part 1)

 

1) Recitation: Intro to Light

Link: Recitation 7_Phys 132_Intro to Light.pdf

* Warn the students about safety concerns when using this equipment (see discussion below).  Some equipment should not be touched until lab (including the glass lenses and the poles and clamps).  The pole clamped to the table should NOT be moved, by students or TAs.

** Before recitation starts, make sure that the previous TA left everything in order: check that all the tables have the needed equipment AND check that all the 90-degree clamps have been removed from the vertical pole clamped to the table.  Be kind and leave the equipment in order for the section that comes after yours!

*** If the recitation runs 10 or 15 minutes over time, that is fine with me.  The students should get as close to finished with the recitation as possible in order to have the necessary concepts for doing the lab.  Do not let recitation run past the 1 hour, 10 minute mark of the 3-hour recitation + lab block.

 

(Break--some groups may not get a break this week, especially if the recitation has run over time...)

 

2) Lab 9, Part 1: Exploring Light and Lenses

Link: NEXUS Physics Labs, 2013-2014

* Before lab starts, make sure that the previous TA left everything in order: check that all the tables have the needed equipment AND check that all the 90-degree clamps have been removed from the vertical pole clamped to the table.  Also check that all the lamps have been turned off/unplugged AND that all the LED light-boxes are switched off.  Be kind and leave the equipment in order for the section that comes after yours!

 

a) Safety and equipment instructions:  Dangers in this lab include the glass lenses (breakable and sharp when broken) and the HOT light sources (turn off/unplug when not in use).  There are no lasers here, so none of the light sources are too dangerous for the eyes--but it is still a good idea not to stare directly into the light sources for too long.  The metal washer that each group has is to be used as practice in loading/un-loading the lens-holder.  Show students how to operate the lens-holder and have them practice with the washer before using the lenses.  Also, please discuss proper handling of lenses--no finger prints on the glass, hold by the edges, do not scratch or bang against other surfaces, etc.  The vertical pole clamped to the table should be left where it is--no one should move it.  Discuss use of the 90-degree clamps with the students--especially the importance of not over-tightening a clamp.

 

b) Make sure to introduce this lab carefully!  Discuss the contrast between deductive and inductive reasoning (this lab is inductive).  Discuss that we are looking into how a microscope works--how does it use lenses to magnify images?  Talk about how the set-up (fixed vertical total length and switching lenses to change magnifications) models a modern microscope.

 

c) As students design their experiments, make sure that you are probing their thinking.  Are they recording uncertainties?  Are these uncertainties reasonable (and not just an instrument limiting error)?  Are the uncertainties the same for all lenses?  Are they sure that their 'parallel rays' are parallel?  Are students sticking to the 'fixed total length' requirement?  Have students tested the extremes of their lenses (largest and smallest f) to be sure that their set-up works before gathering their data?  Are students recording magnification data?  All data should be collected this first week, but the equipment will be available next week if students need to back up and take/re-take some data.

 

d) Be sure to check the students' measured focal lengths before they move on to the second investigation.  If the numbers are too far off, check their method--the most likely culprit is rays that aren't parallel.  They may also have optical elements that are not aligned or are not orthogonal to the optical axis.  In case you lost the paper, the color codes on the focal lengths of the lenses are:

Black = +10 cm

Red = +15 cm

Green = +20 cm

Yellow = +30 cm (Diverging Yellow = -30 cm --there as an instructive contrast, not used in actual lab measurements)

Orange = +50 cm

 

e) Remind the students that they should be carefully recording their data (and the uncertainties) AS WELL AS carefully recording their experimental design choices and the reasoning behind those choices.  The experimental protocol they create should be complete and precise in its use of language.

 

f) Make sure that EACH student has a copy of ALL of the data (numbers and Excel & Word documents) BEFORE leaving the lab.

 

g) Leaving the lab in order for the next group: Check that all the tables have the needed equipment AND check that all the 90-degree clamps have been removed from the vertical pole clamped to the table.  Also check that all the lamps have been turned off/unplugged AND that all the LED light-boxes are switched off.  Make sure that all the lab papers are also sorted and stacked neatly at the back of the room by the printer.  Be kind and leave the room in order for the section that comes after yours!

 

Comments (0)

You don't have permission to comment on this page.