Measuring Glass Surface Temperature

[Guest Cyborg Samurai]

Hi everyone, I'm new to these forums and require some help. I was given an experiment planning exercise by my physics teacher and need some idea of what to do. Basically, I need to investigate the relationship between the power supplied to a filament lamp and the temperature of the lamp's glass envelope. For the power adjustment I intend to use a variable resistor, power pack, voltmeter and ammeter setup (bearing in mind the P=IV). What should I use to measure the temperature of the glass, though? I've done some research into thermocouples, but I'm still not sure how exactly they work. Any suggestions would be appreciated. Thanks!

[hierarch]

IMO, using thermocouple will be a good way to measure the temperature of the glass.

[Guest Cyborg Samurai]

IMO, using thermocouple will be a good way to measure the temperature of the glass.

 

How would I do this, though?

[YT2095]

for a start you`de need to position them in a few places, as the heat will be greater at the top of the bulb than at the bottom.

you`ll also need to check the temp range on the device, some are acurate only a certain range, I`de go to a max of 250c, that`ll be more than adequate for a standard 100W bulb. you may also use the digital heat probes used in kitchens to test if meat it cooked!

 

I sugest using teflon tape to attatch these and a silicon grease or Zinc Oxide based heat transfer compound to make a more intimate contact with the bulb (do it while it cold and switched of tho!)

[hierarch]

How would I do this, though?

 

Besides thermocouples, you also need a digital temperature meter (I don't get its exact name) for measuring the temperature. The glass and the digital temperature meter are linked by the thermocouples and then the digital temperature meter would display the temperature of the glass. A guy in our group measure the temperature of a reactor with such a method.

 

You can also use your PC to determine the temperature, as described at this site:

http://www.windmill.co.uk/thermocouple.html

[hierarch]

I have found more sites described methods for measuring temperature:

 

http://www.datatranslation.com/emails/120303-usb-dt9805.htm

http://www.sensoray.com/html/tcapp.htm

http://zone.ni.com/devzone/conceptd.nsf/webmain/4C54819521D3503786256D73006E8BE9?opendocument

 

These sites could be usefull to solve your problem.

[Guest Cyborg Samurai]

Thanks for the info, people. I'll sift through it and let you know if it helps!

[YT2095]

Heirarch, Nice links!

[Guest Nemesis]

you may also use the digital heat probes used in kitchens to test if meat it cooked!

 

I sugest using teflon tape to attatch these and a silicon grease or Zinc Oxide based heat transfer compound to make a more intimate contact with the bulb (do it while it cold and switched of tho!)

 

can u tell me what digital heat probes r used for in this experiement and also teflon tape why use it and also what u mean by "do it while it cold and switched of tho". do u mean u only do this in cold temperature not in hot?

thanks

[felinlasv]

Teflon tape will be able to resist the heat and thus won't melt or burn. And you have to this when your lamp os cold because otherwise you'll burn your fingers..

[Guest quicksilver_4000]

As mentioned by felinasv the teflon tape will be able to resist the heat as it holds the thermocouples in place, it will also expand with the glass. Not having this expansion quality may cause the glass to break as it heats up and expands. A digital probe would be required to to measure the temperature of the 'cold' or reference junction os the thermocouple. If you dont know (sorry if you do) how thermocouples work its through having two very different metals attached at an end sometimes known as the 'hot' junction, this 'hot' junction is placed on the surface that you wish to measure the temperature of. As the temperature changes a voltage is formed between these metals known as a 'seeback' voltage. This voltage is proportional to the temperature difference between the 'hot' and 'cold' (reference) junctions. Therefore a digital probe should be used to measure the temperatue. The best way of attaining a final temperature reading would be to interface the thermocouples and digital probe with some sort of aquisition unit, this information could then be fed into a computer and some software used to calcualte the temperature.

 

Cheers

 

Glove

[BPHgravity]

Use an IR thermometer. These are non-contact devices that are extremely accurate.

 

http://www.toolsource.com/ost//product.asp?brand_id=&sourceid=googleraytek&dept_id=500&pf_id=92165&mscssid=6FKAP1S6CNMG8NVDD1DB7NM35BUJ9DC7