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The Perfect Microwave Absorber


Andy G4JNT
 

The chaps at Mr Kipling cakes need to be recruited at certain microwave companies that make dummy loads.  They appear to have invented the perfect microwave absorber material.

Mr. Kipling Eccles cakes come with a warning "Do Not Microwave"  Well ...
Rules are for the Guidance of etc etc. ...
So ten seconds at 850 Watts

And were the innards HOT !

Each cake weighs 50g and lets assume this is all the fruit/jam inside
Energy = 8500 Joules, which, assuming the specific heat of Eccles cake innards  is the same as that of water, 4200J/K/kg, should have raised the temperature  40C.   They would have been about 15C to start with, but those innards tasted a lot hotter than 55C.

Is the specific heat of jam / fruit significantly less than that of water ?   Coz that's the only real explanation I can think of - the cooker isn't generating more power than it should.




Martin Phillips G4CIO
 

Quick answer: yes.

Longer answer: SHC of pure sugar around 1.4 J/g/K, jam is roughly 50% sugar. Raisins seem to be 1.63 J/g/K but oddly currants (very similar one might think) 4.06. <https://www.engineeringtoolbox.com/specific-heat-capacity-food-d_295.html>



On 12/10/20 3:56 PM, Andy G4JNT wrote:

Is the specific heat of jam / fruit significantly less than that of water ?   Coz that's the only real explanation I can think of - the cooker isn't generating more power than it should.





Andy G4JNT
 

AH...
Explains thing

In fact, no food seems as high a Sp. Heat as water, except cucumber, and that's 95% water anyway 
Can't be too many currents in there tho.   Perhaps I'd better try a proper Eccles cake.   (Good excuse to go to the next Farmers Market)



On Mon, 12 Oct 2020 at 16:27, Martin Phillips G4CIO <martin@...> wrote:
Quick answer: yes.

Longer answer: SHC of pure sugar around 1.4 J/g/K, jam is roughly 50% sugar. Raisins seem to be 1.63 J/g/K but oddly currants (very similar one might think) 4.06. <https://www.engineeringtoolbox.com/specific-heat-capacity-food-d_295.html>



On 12/10/20 3:56 PM, Andy G4JNT wrote:

Is the specific heat of jam / fruit significantly less than that of water ?   Coz that's the only real explanation I can think of - the cooker isn't generating more power than it should.





Mike Willis
 

Surely the atmosphere on a contest weekend is the best at absorbing signals?
--
Mike G0MJW


Clint Sharp <cjaysharp@...>
 

I feel we should run a properly controlled and scientifically rigorous experiment if Eccles cakes are involved, if you could post some control samples to me I can perform microwave testing too?

Seriously though, jam making in a microwave is not for the faint hearted because of the SHC of sugar, you can get rather spectacular and labour intensive messes as well as some rather serious burns.


On Mon, 12 Oct 2020 at 17:07, Andy G4JNT <andy.g4jnt@...> wrote:
AH...
Explains thing

In fact, no food seems as high a Sp. Heat as water, except cucumber, and that's 95% water anyway 
Can't be too many currents in there tho.   Perhaps I'd better try a proper Eccles cake.   (Good excuse to go to the next Farmers Market)



On Mon, 12 Oct 2020 at 16:27, Martin Phillips G4CIO <martin@...> wrote:
Quick answer: yes.

Longer answer: SHC of pure sugar around 1.4 J/g/K, jam is roughly 50% sugar. Raisins seem to be 1.63 J/g/K but oddly currants (very similar one might think) 4.06. <https://www.engineeringtoolbox.com/specific-heat-capacity-food-d_295.html>



On 12/10/20 3:56 PM, Andy G4JNT wrote:

Is the specific heat of jam / fruit significantly less than that of water ?   Coz that's the only real explanation I can think of - the cooker isn't generating more power than it should.






--
Clint. M0UAW IO83

No trees were harmed in the sending of this mail. However, a large number of electrons were greatly inconvenienced.


Chris G8BKE
 

Not just Eccles cakes but any Christmas mince pies too!

C