Australia's Science Forum

Teacher has asked me to purchase "some resistors". So, for someone who only has HSC physics, which ones? (we are a Middle School campus)

You need to be told
What value in Ohms symbol omega
What Wattage, How much current he is going to draw through them?
Get back when you have this info and we will guide you through it

We get all of ours from Wiltronics. We get the little wooden ones rather than ceramic but there has been a lot of discussion on here (I think) about them. Do a bit of a search and then go back to the teacher armed with knowledge like Ocker said, they need to tell you which ones to get. If you have some time, get the Wiltronics catalogue (you could probably find them online and ask for one) and take the pages of resistors to them and ask them to circle or put a * next to the ones they want, then you can't get it wrong (and if you do, you've got a come-back "Look, that's what you said") Also it means you will know what to order when they need replacing so keep the page(s) for future reference!

Last year, we ended up buying Resistor Sets made by IEC. They are not cheap ($80) but they are worth it and easy to use apparently. I do not pretend to understand electricity but these are made so that the school 12v transformer will not overload or damage the resistors. Ideal for Junior to Middle school.

Also go onto Jarcar web site
print out the couple of pages on resistors and let him pick
You are not a mind reader, so don't know what he plans for them

Thanks all. I though it may have been a "these are the standard ones" given he didn't give me specifics, but I will (once again *sigh*) tell him I need to know his exact requirements.

If there is a "standard resistor" that is commonly found in schools, it would probably be the old "Water Filled" resistors in the clear plastic jar, similar to what Serrata sells as "Resistance in Clear Case" (Catalog Numbers 1011015 - 1011022). (about $8 - $9 each) These can get a little messy as you are supposed to fill the jar with water before you use them (to help keep the resistor cool) and empty it at the end of the experiment. Most teachers don't bother to fill the jar with water and so there is usually a few in the set with melted jars!!

Serrata also sells "Resistors Mounted on Clear Stand" which look OK. They have 2, 5, 10 and 20 ohm 10 Watt "wire wound" resistors mounted on acrylic stands with banana plug sockets, and DON't need to be filled with water. (about $12 each)

(No, I don't work for Serrata. I just have their catalogue on my desk)

Jacar sell the same 10 Watt resistors without the stand for about $1,60 each and the banana posts for $1.95 each (you would need 2). If you mounted them in a plastic "Specimen Jar" (with the yellow screw on lid) you could make your own for under $6. Probably more work than the $3 saving, though.

Cheers
Ian