Absorption Spectra Demonstration

[Tonytech]

the rh one is an old griffin one with round plugs for the tube part. if you have the tubes you must have the housing and transformer unless someone threw them away.

View attachment 11123

I have a couple of these, Heavy buggers.
They are semi retired, as we have a slightly more modern one and only use it as a demo, rater than a class prac.
I have a vague memory of using a sodium lamp and a spectrometer as part of the "A" level practical exam.. circa 1990?

 

[Nick Mitchener]

I have a couple of these, Heavy buggers.
They are semi retired, as we have a slightly more modern one and only use it as a demo, rater than a class prac.
I have a vague memory of using a sodium lamp and a spectrometer as part of the "A" level practical exam.. circa 1990?

I use bright LEDs with spectrometers usually, the yellow seems to give a single colour quite well. I'm not sure an LED is bright enough for some of the jobs might it might be.

 

[captainlabmagnet]

We do this experiment. We used to use sodium pencils but they appear to no longer be available. Instead, we use some corrugated cardboard soaked in saturated NaCl solution. We then wrap the cardboard round the collar of a bunsen burner and light the bunsen. It's a bit messy, but it works. For a white light, we have a 12v halogen lamp, it's an old Griffin and George lamp, but again, it does the job.

Any photos of what the old sodium pencils actually look like? Can't seem to find them online at all.

 

[captainlabmagnet]

I spotted an engineer replacing them for LED street lights. I had a word and explained that I was a Stem Ambassador and he gave me a complete light fitting and a spare tube. I took out the light sensor and mounted it on a retort stand.

I miss the warm glow of sodium street lamps. Especially if you were going a drive at night

 

[captainlabmagnet]

the rh one is an old griffin one with round plugs for the tube part. if you have the tubes you must have the housing and transformer unless someone threw them away.

View attachment 11123

Think the former technician did exactly that. Lot of missing bits for different pieces of equipment unfortunately.

 

[Nick Mitchener]

Think the former technician did exactly that. Lot of missing bits for different pieces of equipment unfortunately.

It's normally teachers who throw stuff away, in a mad tidying frenzy when there isn't a tech to stop them

 

[PhysicsPrep]

Any photos of what the old sodium pencils actually look like? Can't seem to find them online at all.

 

[PhysicsPrep]

Here's a photo. The board pen is for scale. You can't get them anymore which is why we have gone over to cardboard soaked in saturated brine and it seems to work very well.

 

[Phystech]

If you don't have a Sodium light, use a Bunsen with a bit of Soda glass in the flame.

 

[captainlabmagnet]

If you don't have a Sodium light, use a Bunsen with a bit of Soda glass in the flame.

Seems easier than using a wick soaked in a sodium salt solution. Still need a sodium light source to pass through the sodium vapour though.

 

[Phystech]

Seems easier than using a wick soaked in a sodium salt solution. Still need a sodium light source to pass through the sodium vapour though.

Use a soda glass rod in a blue flame.

 

[captainlabmagnet]

Use a soda glass rod in a blue flame.

That would produce the sodium vapour I'm looking for but I'd still need a sodium lamp to shine through the vapour like in the videos I linked earlier

 

[Nick Mitchener]

That would produce the sodium vapour I'm looking for but I'd still need a sodium lamp to shine through the vapour like in the videos I linked earlier

You won't get one cheaper than the one still on ebay for £55.

 

[captainlabmagnet]

You won't get one cheaper than the one still on ebay for £55.

I asked about buying from ebay but my local authority doesn't allow it unfortunately. Would save them a lot of money as well. If it's still listed when I get paid I might snatch it up

 

[Nick Mitchener]

I asked about buying from ebay but my local authority doesn't allow it unfortunately. Would save them a lot of money as well. If it's still listed when I get paid I might snatch it up

At my last school I could buy on ebay and claim back with the invoice. At this school I can do the same or Finance will actually bid on ebay themselves. Previous school was an Academy, this one is Local Authority.

There is usually a route to these things, Finance officers are the type to like a bargain. It is sold tested as working too so you have no problem getting your money back if it doesn't. The one I bought from them is being used in a lesson now.