- #1
jeffinbath
Gold Member
- 35
- 14
Following on from the recent discussion on the gap size in the metal grill covering the door of a microwave oven, I thought up a way to actually enable one to see some of the standing microwave patterns going on in a typical oven .
I bought a 20” x 20”cobalt chloride soaked cloth from Amazon [these are sold as water-leak detectors] and cut out about a 30 cm square piece which would just fit the floor of my oven. I then needed to convert this bit of blue cloth to a slightly off-white one by leaving the cloth over-night in a 100% (approx.) relative humidity chamber without actually letting it contact liquid water. I used a large transparent polypropylene box with a lid and held the cloth on a wall of the box using pairs of small ferrite magnets and covered the floor of the box with a soaking-wet newspaper.
I then removed the glass plate and its support from the oven and wiped off any water condensation from the 6 surfaces of the oven before placing my bit of white cloth on the oven floor. I then gave it 30 seconds of full power. I then put the cloth on a fridge door and held it in place with ferrite magnets and took photo 1. I then repeated the whole operation but this time hung the cloth from the roof of the oven by holding it in place with 2 ferrite magnets.
The conversion of the hydrated CoCl2 to its bright blue anhydrous form seemed to occur more rapidly in the vertical set-up . This is shown in photo 2. The need for food to be rotated is certainly demonstrated here.
One feature that did really surprise me was that ferrite magnets , famous for being electrical insulators, could actually get quite hot on the walls of the oven and even before the 30 seconds irradiation time was up , one magnet cracked in half. (shown in bottom rhs of photo 2 ). Could someone explain this please ?
I bought a 20” x 20”cobalt chloride soaked cloth from Amazon [these are sold as water-leak detectors] and cut out about a 30 cm square piece which would just fit the floor of my oven. I then needed to convert this bit of blue cloth to a slightly off-white one by leaving the cloth over-night in a 100% (approx.) relative humidity chamber without actually letting it contact liquid water. I used a large transparent polypropylene box with a lid and held the cloth on a wall of the box using pairs of small ferrite magnets and covered the floor of the box with a soaking-wet newspaper.
I then removed the glass plate and its support from the oven and wiped off any water condensation from the 6 surfaces of the oven before placing my bit of white cloth on the oven floor. I then gave it 30 seconds of full power. I then put the cloth on a fridge door and held it in place with ferrite magnets and took photo 1. I then repeated the whole operation but this time hung the cloth from the roof of the oven by holding it in place with 2 ferrite magnets.
The conversion of the hydrated CoCl2 to its bright blue anhydrous form seemed to occur more rapidly in the vertical set-up . This is shown in photo 2. The need for food to be rotated is certainly demonstrated here.
One feature that did really surprise me was that ferrite magnets , famous for being electrical insulators, could actually get quite hot on the walls of the oven and even before the 30 seconds irradiation time was up , one magnet cracked in half. (shown in bottom rhs of photo 2 ). Could someone explain this please ?
Attachments
Last edited by a moderator: