From jjaffrey at slingshot.co.nz Sun Aug 3 04:44:19 2008 From: jjaffrey at slingshot.co.nz (Jonathan Jaffrey) Date: Sun, 3 Aug 2008 20:44:19 +1200 Subject: Class sets of diffraction gratings Message-ID: <57F7C9B562E7451D90A84A7BC9EE71EB@handjstudy> Hi, I'm keen to increase the number of Year 13 (or Y12!) class practicals done with gratings. I'm offering class sets of gratings with a free CD of worksheets & PowerPoints of basic theory & experiments as follows: 20 off (10x1000line/mm plus 10x500line/mm) for $80 plus freight, 40 off (20x1000line/mm plus 20x500line/mm) for $140. Good quality replica gratings protected by wipe clean plastic in 35mm slides to fit standard rayboxes. Order from: jjaffrey at slingshot.co.nz Jonathan Jaffrey -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080803/dc52c95a/attachment.html From jwatson at stbedes.school.nz Sun Aug 10 18:24:08 2008 From: jwatson at stbedes.school.nz (John Watson) Date: Mon, 11 Aug 2008 10:24:08 +1200 Subject: Electrical power loss as heat Message-ID: <003801c8fb37$cec41870$b197a8c0@stbedes.school.nz> Hi When looking at power lost as heat in transmission lines, can someone please explain why we use P=i^2R but cannot use P=V^2/R? Aren't they equivalent expressions? thanks _________________________________________ John Watson St Bede's College Christchurch E-Mail: jwatson at stbedes.school.nz -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080811/217981a1/attachment.html From christchurch at futureintech.org.nz Sun Aug 10 20:34:32 2008 From: christchurch at futureintech.org.nz (Colin Bell) Date: Mon, 11 Aug 2008 12:34:32 +1200 Subject: Electrical power loss as heat In-Reply-To: <003801c8fb37$cec41870$b197a8c0@stbedes.school.nz> References: <003801c8fb37$cec41870$b197a8c0@stbedes.school.nz> Message-ID: Hi John Current can be calculated directly from input voltage and total resistance (load plus transmission wire) Using I^2xR gives power loss immediately. To use V^2/R we first need to calculate voltage loss. Voltage loss can't be calculated initially, since we don't know current initially, so we have to do that anyway. Once current is calculated, voltage loss is calculated from Ohm's Equation, V= IxR(line) Using V^2/R now gives the power loss. Takes longer! Cheers Colin Colin Bell Futureintech Facilitator Christchurch Futureintech is an IPENZ initiative Host Meyer Consulting Ltd PO Box 8424 Riccarton T Host 03 348 2174 T Home 03 351 3918 Mobile 021 479 890 www.futureintech.org.nz Opinions expressed herein are those of the writer and do not necessarily reflect IPENZ policy. ________________________________ From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of John Watson Sent: Monday, 11 August 2008 10:24 a.m. To: Physics discussion group Subject: Electrical power loss as heat Hi When looking at power lost as heat in transmission lines, can someone please explain why we use P=i^2R but cannot use P=V^2/R? Aren't they equivalent expressions? thanks _________________________________________ John Watson St Bede's College Christchurch E-Mail: jwatson at stbedes.school.nz -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080811/a4c9982e/attachment.html From francis.Bryden at stcuthberts.school.nz Sun Aug 10 21:42:58 2008 From: francis.Bryden at stcuthberts.school.nz (Bryden, Francis) Date: Mon, 11 Aug 2008 13:42:58 +1200 Subject: loss in transmission lines Message-ID: <6AC36C5F0F8E364CBEC8178DD499F3EF01D730E5@stcc-exchange.stcuthberts.local> Hi John Hi JohnWith transmission lines, there are two voltages to consider. 1. The voltage between the wires (or the terminal voltage of the transformer) 2. The voltage drop along the length of the wire. You could use either equation to find the power loss as long as you realize that the "V" is the voltage drop along the length of the wire. This is tricky to measure, so its easier to use P = I^2 R to calculate the power loss and P = VxI to find the power transferred where "V" is the voltage between the wires Fro this it is easy to see why you want a small I and a big V regards ................ Francis Thanks ................ Francis Francis Bryden HoD Physics St Cuthbert's College 122 Market Rd or Box 26 020 Epsom Epsom Auckland 1051 Auckland 1344 New Zealand New Zealand ph: 64 9 5204159 ext 7808 fbryden at stcuthberts.school.nz P Please consider the environment before printing this email -------------------------------------------------------- This message (and any associated files) is intended only for the use of the individual or entity to which it is addressed and may contain information that is confidential, subject to copyright or constitutes a trade secret. If you are not the intended recipient you are hereby notified that any dissemination, copying or distribution of this message, or files associated with this message, is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and deleting it from your computer. Messages sent to and from us may be monitored. -------------------------------------------------------- This email has been checked by Symantec Mail Security for Exchange. 13:42:59 Mon 11 Aug 2008 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080811/6fc8e13d/attachment-0001.html From g.foster at clear.net.nz Mon Aug 11 00:21:21 2008 From: g.foster at clear.net.nz (g.foster) Date: Mon, 11 Aug 2008 16:21:21 +1200 Subject: Circuit diagram drawing programs Message-ID: <489fbe41.33c.42cf.16193@clear.net.nz> We have tried to use Croc Clips as our circuit diagram program for drawing then cutting and pasting into our other documents, but we do not find it satisfactory. Can anyone advise a better ICT program please and how to get it? Does anyone use a freeware or shareware program? Thanks Graham Foster EGGS fs at eggs.school.nz Graham Foster Director of Science, EGGS AMI Learned Society From jjaffrey at slingshot.co.nz Mon Aug 11 20:12:40 2008 From: jjaffrey at slingshot.co.nz (Jonathan Jaffrey) Date: Tue, 12 Aug 2008 12:12:40 +1200 Subject: Circuit diagram drawing Vol 8, Issue 3 In-Reply-To: References: Message-ID: <15B1DB32EC8E48C5BA6ACA73335C141C@handjstudy> Hi, I've just done a word document we can all use. It has all the basic symbols done in groups in MS Draw. You can select a group then copy it into your worksheet, slide etc then resize, rotate etc to suit. I'll attach it here & try to post it to NZIP site too. =) Jonathan Jaffrey -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of phys-teach-talk-request at nzip.org.nz Sent: Tuesday, 12 August 2008 4:00 a.m. To: phys-teach-talk at nzip.org.nz Subject: Phys-teach-talk Digest, Vol 8, Issue 3 Send Phys-teach-talk mailing list submissions to phys-teach-talk at nzip.org.nz To subscribe or unsubscribe via the World Wide Web, visit http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz or, via email, send a message with subject or body 'help' to phys-teach-talk-request at nzip.org.nz You can reach the person managing the list at phys-teach-talk-owner at nzip.org.nz When replying, please edit your Subject line so it is more specific than "Re: Contents of Phys-teach-talk digest..." Today's Topics: 1. Circuit diagram drawing programs (g.foster) ---------------------------------------------------------------------- Message: 1 Date: Mon, 11 Aug 2008 16:21:21 +1200 From: "g.foster" Subject: Circuit diagram drawing programs To: Phys-teach-talk at nzip.org.nz Message-ID: <489fbe41.33c.42cf.16193 at clear.net.nz> We have tried to use Croc Clips as our circuit diagram program for drawing then cutting and pasting into our other documents, but we do not find it satisfactory. Can anyone advise a better ICT program please and how to get it? Does anyone use a freeware or shareware program? Thanks Graham Foster EGGS fs at eggs.school.nz Graham Foster Director of Science, EGGS AMI Learned Society ------------------------------ _______________________________________________ Phys-teach-talk mailing list Phys-teach-talk at nzip.org.nz http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz End of Phys-teach-talk Digest, Vol 8, Issue 3 ********************************************* -------------- next part -------------- A non-text attachment was scrubbed... Name: Electrical Symbols.doc Type: application/msword Size: 45568 bytes Desc: not available Url : http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080812/824486b6/attachment-0001.doc From bpantry at carmel.school.nz Wed Aug 13 19:20:18 2008 From: bpantry at carmel.school.nz (Bev Pantry) Date: Thu, 14 Aug 2008 11:20:18 +1200 Subject: cellphones Message-ID: Two questions, not directly related to the curriculum but of interest. My Y13 students have asked how dangerous is the radiation when using cell phones or cordless phones. Secondly, apparently there is something that you can buy to insert in the cell phone that absorbs /stops the radiation, how effective is this? Any ideas? Bev Pantry Carmel College -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080814/4117ca74/attachment.html From dking at christscollege.com Wed Aug 13 19:31:12 2008 From: dking at christscollege.com (David King) Date: Thu, 14 Aug 2008 11:31:12 +1200 Subject: cellphones In-Reply-To: References: Message-ID: <70E5FECA-DC86-42CC-BF11-7BB736677E1F@christscollege.com> Funnily enough this came up on PTNC recently http://health.msn.com/health-topics/cancer/articlepage.aspx?cp- documentid=100211877&page=1 might be relevant to the discussion. Lots of websites discount the effects. Hmmm Texting seems to be the safest thing! Hmmmm - interesting use of 'safest' - I wonder what we mean by danger? Cheers David King Physics HoD Christ's College Private Bag 4900 Christchurch New Zealand On 14/08/2008, at 11:20 AM, Bev Pantry wrote: > Two questions, not directly related to the curriculum but of interest. > > My Y13 students have asked how dangerous is the radiation when > using cell phones or cordless phones. Secondly, apparently there is > something that you can buy to insert in the cell phone that > absorbs /stops the radiation, how effective is this? > > > > Any ideas? > > > > Bev Pantry > > Carmel College > > _______________________________________________ > Phys-teach-talk mailing list > Phys-teach-talk at nzip.org.nz > http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080814/cd59633a/attachment.html From g.foster at clear.net.nz Thu Aug 14 00:55:53 2008 From: g.foster at clear.net.nz (g.foster) Date: Thu, 14 Aug 2008 16:55:53 +1200 Subject: Long life light bulbs Message-ID: <48a3bad9.1e2.20d9.28026@clear.net.nz> In the recent Investigate magazine Ian Wishhart has an article re how DANGEROUS the new coiled light bulbs are. Has anyone else read it?? Any comments? If you would like a copy please email me fs at eggs.school.nz Graham Foster Graham Foster Director of Science, EGGS AMI Learned Society From parkerprice at clear.net.nz Thu Aug 14 02:59:23 2008 From: parkerprice at clear.net.nz (Kerry Parker and Andy Price) Date: Thu, 14 Aug 2008 18:59:23 +1200 Subject: Long life light bulbs In-Reply-To: <48a3bad9.1e2.20d9.28026@clear.net.nz> References: <48a3bad9.1e2.20d9.28026@clear.net.nz> Message-ID: <1416D1A702B84AFA99BD5ACF48D7BB98@study> Thanks Graham. The article looks like an excellent example of unbalanced, biased reporting, high on SENSATIONALISM. Yes, the use of capitals is UNNCESCCESARY!!! It is good to question these things. It is sad that the word 'investigate' is associated with this type of journalism. I belive quite passionately that we should be teaching our students to see through scare-mongering flakey 'science' and make reasoned decisions, as adults, based consideration of a range of evidence of varying validity. Whether it is Moon hoaxes, the oil companies supressing the water-powered car, cell phones as mind-control or food supplements , we all need to get things in proportion and make up our own minds. Discussion of relative risk and what might be deemed dangerous, or even DANGEROUS, is also valueable. The evidence that I have seen is that people, with Kiwis in particlar, being pretty poor at assessing relative risk. Happy debating Kerry ----- Original Message ----- From: "g.foster" To: Sent: Thursday, August 14, 2008 4:55 PM Subject: Long life light bulbs > In the recent Investigate magazine Ian Wishhart has an > article re how DANGEROUS the new coiled light bulbs are. Has > anyone else read it?? Any comments? > > If you would like a copy please email me fs at eggs.school.nz > > Graham Foster > > Graham Foster > Director of Science, EGGS > AMI Learned Society > > _______________________________________________ > Phys-teach-talk mailing list > Phys-teach-talk at nzip.org.nz > http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz From johnb at delasalle.co.nz Thu Aug 14 16:31:25 2008 From: johnb at delasalle.co.nz (John Bennet) Date: Fri, 15 Aug 2008 08:31:25 +1200 Subject: Long life light bulbs In-Reply-To: <1416D1A702B84AFA99BD5ACF48D7BB98@study> References: <48a3bad9.1e2.20d9.28026@clear.net.nz> <1416D1A702B84AFA99BD5ACF48D7BB98@study> Message-ID: <48A4961D.6010104@delasalle.co.nz> An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080815/3e9e41df/attachment.html From jwatson at stbedes.school.nz Thu Aug 14 16:46:59 2008 From: jwatson at stbedes.school.nz (John Watson) Date: Fri, 15 Aug 2008 08:46:59 +1200 Subject: Safety of eco bulbs Message-ID: <001701c8fe4e$e5e28130$4b97a8c0@stbedes.school.nz> I don't read Investigate, but there is an article on the Stuff website regarding eco bulb safety. "The Government's safety agency has warned the Fire Service about the potential hazard of energy-saving lightbulbs, a memorandum to firefighters reveals. The memo, of which The Dominion Post has a copy, warns that compact fluorescent lamps, or eco bulbs, are reported to be melting, blowing up and blackening surrounding electrical equipment." John Watson St Bede's College > Date: Thu, 14 Aug 2008 16:55:53 +1200 > From: "g.foster" > Subject: Long life light bulbs > To: Phys-teach-talk at nzip.org.nz > Message-ID: <48a3bad9.1e2.20d9.28026 at clear.net.nz> > > In the recent Investigate magazine Ian Wishhart has an > article re how DANGEROUS the new coiled light bulbs are. Has > anyone else read it?? Any comments? > > If you would like a copy please email me fs at eggs.school.nz > > Graham Foster > > Graham Foster > Director of Science, EGGS > AMI Learned Society > > > > ------------------------------ > > Message: 4 > Date: Thu, 14 Aug 2008 18:59:23 +1200 > From: Kerry Parker and Andy Price > Subject: Re: Long life light bulbs > To: g.foster at clear.net.nz, Phys-teach-talk at nzip.org.nz > Message-ID: <1416D1A702B84AFA99BD5ACF48D7BB98 at study> > Content-Type: text/plain; format=flowed; charset=iso-8859-1; > reply-type=original > > Thanks Graham. The article looks like an excellent example of unbalanced, > biased reporting, high on SENSATIONALISM. Yes, the use of capitals is > UNNCESCCESARY!!! It is good to question these things. It is sad that the > word 'investigate' is associated with this type of journalism. I belive > quite passionately that we should be teaching our students to see through > scare-mongering flakey 'science' and make reasoned decisions, as adults, > based consideration of a range of evidence of varying validity. Whether it > is Moon hoaxes, the oil companies supressing the water-powered car, cell > phones as mind-control or food supplements , we all need to get things in > proportion and make up our own minds. > Discussion of relative risk and what might be deemed dangerous, or even > DANGEROUS, is also valueable. The evidence that I have seen is that people, > with Kiwis in particlar, being pretty poor at assessing relative risk. > Happy debating > Kerry > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080815/63570899/attachment.html From jjaffrey at slingshot.co.nz Fri Aug 15 19:33:15 2008 From: jjaffrey at slingshot.co.nz (Jonathan Jaffrey) Date: Sat, 16 Aug 2008 11:33:15 +1200 Subject: Eco bulbs: Phys-teach-talk Digest, Vol 8, Issue 6 In-Reply-To: References: Message-ID: <849D1425F6644533A8994509C160066A@handjstudy> Hmmm The integrated ballast in these bulbs could well fail occasionally as with any electronics (TVs etc). Halogen bulbs also fail at high temps & have been linked to house fires. The volumes of mercury are likely to be insignificant. To return to Kerry's point - surely a balanced take on this would be that it'd be better to spend money on insulating homes & hot water supplies than putting all this capital expense into reducing lighting costs?? Jonathan Jaffrey -----Original Message----- From: phys-teach-talk-bounces at nzip.org.nz [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of phys-teach-talk-request at nzip.org.nz Sent: Saturday, 16 August 2008 4:01 a.m. To: phys-teach-talk at nzip.org.nz Subject: Phys-teach-talk Digest, Vol 8, Issue 6 Send Phys-teach-talk mailing list submissions to phys-teach-talk at nzip.org.nz To subscribe or unsubscribe via the World Wide Web, visit http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz or, via email, send a message with subject or body 'help' to phys-teach-talk-request at nzip.org.nz You can reach the person managing the list at phys-teach-talk-owner at nzip.org.nz When replying, please edit your Subject line so it is more specific than "Re: Contents of Phys-teach-talk digest..." Today's Topics: 1. Re: Long life light bulbs (John Bennet) 2. Re: Safety of eco bulbs (John Watson) ---------------------------------------------------------------------- Message: 1 Date: Fri, 15 Aug 2008 08:31:25 +1200 From: John Bennet Subject: Re: Long life light bulbs To: Phys-teach-talk at nzip.org.nz Message-ID: <48A4961D.6010104 at delasalle.co.nz> Content-Type: text/plain; charset="us-ascii" An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/2008081 5/3e9e41df/attachment-0001.html ------------------------------ Message: 2 Date: Fri, 15 Aug 2008 08:46:59 +1200 From: "John Watson" Subject: Re: Safety of eco bulbs To: Message-ID: <001701c8fe4e$e5e28130$4b97a8c0 at stbedes.school.nz> Content-Type: text/plain; charset="iso-8859-1" I don't read Investigate, but there is an article on the Stuff website regarding eco bulb safety. "The Government's safety agency has warned the Fire Service about the potential hazard of energy-saving lightbulbs, a memorandum to firefighters reveals. The memo, of which The Dominion Post has a copy, warns that compact fluorescent lamps, or eco bulbs, are reported to be melting, blowing up and blackening surrounding electrical equipment." John Watson St Bede's College > Date: Thu, 14 Aug 2008 16:55:53 +1200 > From: "g.foster" > Subject: Long life light bulbs > To: Phys-teach-talk at nzip.org.nz > Message-ID: <48a3bad9.1e2.20d9.28026 at clear.net.nz> > > In the recent Investigate magazine Ian Wishhart has an > article re how DANGEROUS the new coiled light bulbs are. Has > anyone else read it?? Any comments? > > If you would like a copy please email me fs at eggs.school.nz > > Graham Foster > > Graham Foster > Director of Science, EGGS > AMI Learned Society > > > > ------------------------------ > > Message: 4 > Date: Thu, 14 Aug 2008 18:59:23 +1200 > From: Kerry Parker and Andy Price > Subject: Re: Long life light bulbs > To: g.foster at clear.net.nz, Phys-teach-talk at nzip.org.nz > Message-ID: <1416D1A702B84AFA99BD5ACF48D7BB98 at study> > Content-Type: text/plain; format=flowed; charset=iso-8859-1; > reply-type=original > > Thanks Graham. The article looks like an excellent example of unbalanced, > biased reporting, high on SENSATIONALISM. Yes, the use of capitals is > UNNCESCCESARY!!! It is good to question these things. It is sad that the > word 'investigate' is associated with this type of journalism. I belive > quite passionately that we should be teaching our students to see through > scare-mongering flakey 'science' and make reasoned decisions, as adults, > based consideration of a range of evidence of varying validity. Whether it > is Moon hoaxes, the oil companies supressing the water-powered car, cell > phones as mind-control or food supplements , we all need to get things in > proportion and make up our own minds. > Discussion of relative risk and what might be deemed dangerous, or even > DANGEROUS, is also valueable. The evidence that I have seen is that people, > with Kiwis in particlar, being pretty poor at assessing relative risk. > Happy debating > Kerry > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/2008081 5/63570899/attachment-0001.html ------------------------------ _______________________________________________ Phys-teach-talk mailing list Phys-teach-talk at nzip.org.nz http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz End of Phys-teach-talk Digest, Vol 8, Issue 6 ********************************************* From xtr118950 at xtra.co.nz Sat Aug 16 19:04:40 2008 From: xtr118950 at xtra.co.nz (Paul King) Date: Sun, 17 Aug 2008 11:04:40 +1200 Subject: Eco bulbs: Phys-teach-talk Digest, Vol 8, Issue 6 In-Reply-To: Message-ID: 2. RE: Eco bulbs: Phys-teach-talk Digest, Vol 8, Issue 6 (Paul King) With respect to the economics of moving to Eco-bulbs. The small capital cost involved with such a switch is repaid with interest within 6 months of installation, and over the lifetime of an eco bulb (20 W) savings amount to about $75 at least. This is electricity not generated, gas not ignited. It is a genuine, major cost saving as well a huge energy efficiency boost. Now to apply the same effort to getting insulation retrofitted. A small saving not commonly discussed is the extended life the new bulbs give to our light fittings. The reduced heat seems to slow the powdering of our plastic fitments. The heat induced decay of fitments has probably been the cause of as many fires as failing ballasts are ever likely to produce. You can hear that I am a convert to Eco-bulbs and so shouldn't be trusted to provide a balanced view in any debate - but we have a bright life and LOW power bills - that much is real. And in the early 60's my wife's unattended science class snitched some mercury. Apparently the whole class put drops in their mouths where the slithering cool in the groves of the tongue produced weirdly sensual sensations! There was no outbreak of mercury poisoning and she remains extraordinarily clever. Paul King On 17/8/08 4:00 AM, "phys-teach-talk-request at nzip.org.nz" wrote: > Send Phys-teach-talk mailing list submissions to > phys-teach-talk at nzip.org.nz > > To subscribe or unsubscribe via the World Wide Web, visit > http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz > or, via email, send a message with subject or body 'help' to > phys-teach-talk-request at nzip.org.nz > > You can reach the person managing the list at > phys-teach-talk-owner at nzip.org.nz > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Phys-teach-talk digest..." > > > Today's Topics: > > 1. RE: Eco bulbs: Phys-teach-talk Digest, Vol 8, Issue 6 > (Jonathan Jaffrey) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Sat, 16 Aug 2008 11:33:15 +1200 > From: "Jonathan Jaffrey" > Subject: RE: Eco bulbs: Phys-teach-talk Digest, Vol 8, Issue 6 > To: > Message-ID: <849D1425F6644533A8994509C160066A at handjstudy> > Content-Type: text/plain; charset="us-ascii" > > Hmmm > The integrated ballast in these bulbs could well fail occasionally as with > any electronics (TVs etc). Halogen bulbs also fail at high temps & have been > linked to house fires. The volumes of mercury are likely to be > insignificant. To return to Kerry's point - surely a balanced take on this > would be that it'd be better to spend money on insulating homes & hot water > supplies than putting all this capital expense into reducing lighting > costs?? > Jonathan Jaffrey > > -----Original Message----- > From: phys-teach-talk-bounces at nzip.org.nz > [mailto:phys-teach-talk-bounces at nzip.org.nz] On Behalf Of > phys-teach-talk-request at nzip.org.nz > Sent: Saturday, 16 August 2008 4:01 a.m. > To: phys-teach-talk at nzip.org.nz > Subject: Phys-teach-talk Digest, Vol 8, Issue 6 > > Send Phys-teach-talk mailing list submissions to > phys-teach-talk at nzip.org.nz > > To subscribe or unsubscribe via the World Wide Web, visit > http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz > or, via email, send a message with subject or body 'help' to > phys-teach-talk-request at nzip.org.nz > > You can reach the person managing the list at > phys-teach-talk-owner at nzip.org.nz > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of Phys-teach-talk digest..." > > > Today's Topics: > > 1. Re: Long life light bulbs (John Bennet) > 2. Re: Safety of eco bulbs (John Watson) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Fri, 15 Aug 2008 08:31:25 +1200 > From: John Bennet > Subject: Re: Long life light bulbs > To: Phys-teach-talk at nzip.org.nz > Message-ID: <48A4961D.6010104 at delasalle.co.nz> > Content-Type: text/plain; charset="us-ascii" > > An HTML attachment was scrubbed... > URL: > http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/2008081 > 5/3e9e41df/attachment-0001.html > > ------------------------------ > > Message: 2 > Date: Fri, 15 Aug 2008 08:46:59 +1200 > From: "John Watson" > Subject: Re: Safety of eco bulbs > To: > Message-ID: <001701c8fe4e$e5e28130$4b97a8c0 at stbedes.school.nz> > Content-Type: text/plain; charset="iso-8859-1" > > I don't read Investigate, but there is an article on the Stuff website > regarding eco bulb safety. > "The Government's safety agency has warned the Fire Service about the > potential hazard of energy-saving lightbulbs, a memorandum to firefighters > reveals. > > > The memo, of which The Dominion Post has a copy, warns that compact > fluorescent lamps, or eco bulbs, are reported to be melting, blowing up and > blackening surrounding electrical equipment." > > John Watson > St Bede's College > >> Date: Thu, 14 Aug 2008 16:55:53 +1200 >> From: "g.foster" >> Subject: Long life light bulbs >> To: Phys-teach-talk at nzip.org.nz >> Message-ID: <48a3bad9.1e2.20d9.28026 at clear.net.nz> >> >> In the recent Investigate magazine Ian Wishhart has an >> article re how DANGEROUS the new coiled light bulbs are. Has >> anyone else read it?? Any comments? >> >> If you would like a copy please email me fs at eggs.school.nz >> >> Graham Foster >> >> Graham Foster >> Director of Science, EGGS >> AMI Learned Society >> >> >> >> ------------------------------ >> >> Message: 4 >> Date: Thu, 14 Aug 2008 18:59:23 +1200 >> From: Kerry Parker and Andy Price >> Subject: Re: Long life light bulbs >> To: g.foster at clear.net.nz, Phys-teach-talk at nzip.org.nz >> Message-ID: <1416D1A702B84AFA99BD5ACF48D7BB98 at study> >> Content-Type: text/plain; format=flowed; charset=iso-8859-1; >> reply-type=original >> >> Thanks Graham. The article looks like an excellent example of unbalanced, > >> biased reporting, high on SENSATIONALISM. Yes, the use of capitals is >> UNNCESCCESARY!!! It is good to question these things. It is sad that the > >> word 'investigate' is associated with this type of journalism. I belive >> quite passionately that we should be teaching our students to see through >> scare-mongering flakey 'science' and make reasoned decisions, as adults, >> based consideration of a range of evidence of varying validity. Whether > it >> is Moon hoaxes, the oil companies supressing the water-powered car, cell >> phones as mind-control or food supplements , we all need to get things in >> proportion and make up our own minds. >> Discussion of relative risk and what might be deemed dangerous, or even >> DANGEROUS, is also valueable. The evidence that I have seen is that > people, >> with Kiwis in particlar, being pretty poor at assessing relative risk. >> Happy debating >> Kerry >> > -------------- next part -------------- > An HTML attachment was scrubbed... > URL: > http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/2008081 > 5/63570899/attachment-0001.html > > ------------------------------ > > _______________________________________________ > Phys-teach-talk mailing list > Phys-teach-talk at nzip.org.nz > http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz > > > End of Phys-teach-talk Digest, Vol 8, Issue 6 > ********************************************* > > > > > > ------------------------------ > > _______________________________________________ > Phys-teach-talk mailing list > Phys-teach-talk at nzip.org.nz > http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz > > > End of Phys-teach-talk Digest, Vol 8, Issue 7 > ********************************************* From bevans at es.co.nz Sun Aug 17 00:05:25 2008 From: bevans at es.co.nz (Bob Evans) Date: Sun, 17 Aug 2008 16:05:25 +1200 Subject: Eco bulbs: In-Reply-To: References: Message-ID: <5.1.1.6.0.20080817160005.02bf90b8@pop.ihug.co.nz> At 11:04 a.m. 17/08/2008 +1200, Paul King wrote: >With respect to the economics of moving to Eco-bulbs. The small capital cost >involved with such a switch is repaid with interest within 6 months of >installation, and over the lifetime of an eco bulb (20 W) savings amount to >about $75 at least. This is electricity not generated, gas not ignited. It >is a genuine, major cost saving as well a huge energy efficiency boost. Now >to apply the same effort to getting insulation retrofitted. I have wondered how much energy is required to manufacture eco-bulbs compared to filament bulbs. This needs to be taken into account when comparing the two types. >And in the early 60's my wife's unattended science class snitched some >mercury. Apparently the whole class put drops in their mouths where the >slithering cool in the groves of the tongue produced weirdly sensual >sensations! There was no outbreak of mercury poisoning and she remains >extraordinarily clever. Even earlier our school dental nurse allowed us to play with mercury using our fingers and I don't think I've been affected adversely (others may disagree, however!). Seriously though, I agree mercury is dangerous but we've had fluorescent lights for decades now. Bob -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080817/1e73f1d6/attachment.html From parkerprice at clear.net.nz Sun Aug 17 04:24:57 2008 From: parkerprice at clear.net.nz (Kerry Parker and Andy Price) Date: Sun, 17 Aug 2008 20:24:57 +1200 Subject: Eco bulbs: In-Reply-To: <5.1.1.6.0.20080817160005.02bf90b8@pop.ihug.co.nz> References: <5.1.1.6.0.20080817160005.02bf90b8@pop.ihug.co.nz> Message-ID: <51D11B6FE4E242EE9405097D80A94DBE@study> I agree with Bob: we should be able to put an energy figure on the production of comoditites such as filament and compact flourescent light bulbs. I used to have a video which put a value in Joule on cars, houses and all sorts of everyday items: it was very dated, so I no longer use it, but I always wondered where the values came from. I once met some very high-powered energy-policy people in Britain on a train: their view was that we do have a value, measured in dollars (because the price reflects the energy cost). I disagree with that assessment because I think that relatively cheap energy in the form of fossil fuels give us a bias. Has anyone seen any energy and enivironmental assessment system that would assess the relative 'good' of the two types of bulbs? It is bound to be flawed, but then at least we can have a meaningful discussion. Unless we try to quantify the risks we can't make any progress. Following the discussion about mercury (good on Paul's wife!!) I was interested to read about Fallon, Nevada which is an acute lymphocytic leukemia cluster . The presence of tunsten in biological and drinking water samples in Fallon, Nevada, has "alarmed public health, environmental and regulatory agencies. " http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TGF-4HTCW5T-S&_user=10&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_version=1&_urlVersion=0&_userid=10&md5=08e168eb617f5239d29002060c45fecd regards Kerry ----- Original Message ----- From: Bob Evans To: phys-teach-talk at nzip.org.nz Sent: Sunday, August 17, 2008 4:05 PM Subject: RE: Eco bulbs: At 11:04 a.m. 17/08/2008 +1200, Paul King wrote: With respect to the economics of moving to Eco-bulbs. The small capital cost involved with such a switch is repaid with interest within 6 months of installation, and over the lifetime of an eco bulb (20 W) savings amount to about $75 at least. This is electricity not generated, gas not ignited. It is a genuine, major cost saving as well a huge energy efficiency boost. Now to apply the same effort to getting insulation retrofitted. I have wondered how much energy is required to manufacture eco-bulbs compared to filament bulbs. This needs to be taken into account when comparing the two types. And in the early 60's my wife's unattended science class snitched some mercury. Apparently the whole class put drops in their mouths where the slithering cool in the groves of the tongue produced weirdly sensual sensations! There was no outbreak of mercury poisoning and she remains extraordinarily clever. Even earlier our school dental nurse allowed us to play with mercury using our fingers and I don't think I've been affected adversely (others may disagree, however!). Seriously though, I agree mercury is dangerous but we've had fluorescent lights for decades now. Bob ------------------------------------------------------------------------------ _______________________________________________ Phys-teach-talk mailing list Phys-teach-talk at nzip.org.nz http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080817/dcc8a583/attachment.html From dking at christscollege.com Tue Aug 19 05:43:23 2008 From: dking at christscollege.com (David King) Date: Tue, 19 Aug 2008 21:43:23 +1200 Subject: Usain Bolt 100m data Message-ID: I got his from a PTNC source. Might be useful for people... see attached for data about Bolt's 100m Olympic dash. Cheers David King Physics HoD Christ's College Private Bag 4900 Christchurch New Zealand -------------- next part -------------- A non-text attachment was scrubbed... Name: Usain Bolt 100m sprint world record analysis#2.xls Type: application/octet-stream Size: 76288 bytes Desc: not available Url : http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080819/a67c3a83/attachment-0001.obj From Jbull at stjohns-hamilton.school.nz Wed Aug 27 16:50:01 2008 From: Jbull at stjohns-hamilton.school.nz (John Bull) Date: Thu, 28 Aug 2008 08:50:01 +1200 Subject: bar magnet question Message-ID: <12D16F4BDB49284C927C4B1BE1CEC4A603F6F0@sj-dc2.internal.stjohns-hamilton.school.nz> Can someone give please give me a satisfying explanation to the following observation from one of my year 13 students. If you put to bar magnets with like poles facing they repel. If you separate them with a keeper (about 2 cm long ) they are both attracted to it. ie. the attractive force to the keeper is greater than repulsive force between the poles. What is going on with field lines here? cheers John Bull St John's College Hamilton -------------- next part -------------- An HTML attachment was scrubbed... URL: http://nzip.org.nz/pipermail/phys-teach-talk_nzip.org.nz/attachments/20080828/44472016/attachment.html From robcampbell at actrix.co.nz Thu Aug 28 11:36:17 2008 From: robcampbell at actrix.co.nz (robcampbell at actrix.co.nz) Date: Fri, 29 Aug 2008 03:36:17 +1200 (NZST) Subject: bar magnet question In-Reply-To: <12D16F4BDB49284C927C4B1BE1CEC4A603F6F0@sj-dc2.internal.stjohns-hamilt on.school.nz> References: <12D16F4BDB49284C927C4B1BE1CEC4A603F6F0@sj-dc2.internal.stjohns-hamilton.school.nz> Message-ID: <49632.86.130.187.47.1219937777.squirrel@my.actrix.co.nz> Hi! I think it's more important to get students thinking in a scientific way than to explain things to them. Why not get a group of students to investigate the field lines and generate their own explanation? (Honestly I don't know the answer, and this is what I'd have to do to find out.) Good luck! Rob Campbell =================== Can someone give please give me a satisfying explanation to the following observation from one of my year 13 students. If you put to bar magnets with like poles facing they repel. If you separate them with a keeper (about 2 cm long ) they are both attracted to it. ie. the attractive force to the keeper is greater than repulsive force between the poles. What is going on with field lines here? cheers John Bull St John's College Hamilton ____________________________________________ Phys-teach-talk mailing list Phys-teach-talk at nzip.org.nz http://nzip.org.nz/mailman/listinfo/phys-teach-talk_nzip.org.nz From john.campbell at canterbury.ac.nz Thu Aug 28 22:59:18 2008 From: john.campbell at canterbury.ac.nz (John Campbell) Date: Fri, 29 Aug 2008 14:59:18 +1200 Subject: cell phones response Message-ID: Martin Gledhill has responded to Bev's question re cell phones. He apologised for the delay as he was in the Chatham Islands when the question was passed to him. John Campbell Bev Pantry of Carmel College asked:- My Y13 students have asked how dangerous is the radiation when using cell phones or cordless phones. Is there something that you can buy to insert in the cell phone that absorbs/stops the radiation. If so how effective is this? Martin Gledhill, a physicist at the Ministry of Health's National Radiation Laboratory, responded. Cellphones and cordless phones are small, relatively low-powered radio transmitters. In use they produce radiofrequency (RF) signals, otherwise known as ?RF radiation?. (This should not be confused with the radiation from x-ray equipment or radioactive sources, which is completely different in its physical properties and the way it interacts with the body.) Because the body is mostly composed of electrically conductive fluid, it absorbs some of the energy in the RF radiation emitted by a cellphone. Ultimately that energy is transformed into heat ? but in such tiny amounts that it would be extremely difficult if not impossible to detect. Video clips of cellphones boiling eggs or popping popcorn are simply special effects. The effects of RF radiation on the body have been investigated extensively. While cellphones and cordless phones are relatively new, they are just applications of radio technology that has been around for a long time. Exposure standards to protect health have been developed from a review of the research data. Cellphones and cordless phones on sale in New Zealand comply with those standards. One question often asked is whether cellphones cause brain tumours. Studies on cellphone users do not show an increased risk of brain tumours in people who have used cellphones for periods up to ten years. There is little known about effects on people who have used cellphones for longer than that. While some studies suggest that there may be a small increased risk of tumours among the heaviest users, this pattern is not consistent and the researchers caution that the finding may be explained by biases in the way the studies were carried out. (For example, hazy recall of how much a phone was used over ten years ago.) Laboratory research on cell cultures and animals exposed over their lifetimes does not show that RF radiation affects tumour incidence. The phone radiates along much of its length. Patches, chips and similar gimmicks do not reduce exposures to RF radiation. If you do want to reduce exposures, there are simple steps you can take: Use the phone in places with a good signal strength, which allows the phone to transmit at reduced power. Phones using the newer CDMA or 3G (UMTS) technologies usually provide much greater reductions in power. Use a hands-free kit. Minimise the length of time spent on calls. Use a conventional land line phone (ie not cordless), or a car kit with an external antenna Send questions to Ask-A-Scientist, PO Box 31-035, Christchurch, or email -:- questions at ask-a-scientist.net