Hi All, Having the following problem I am trying to solve I am an electronics guy some of e physics eludes me in my calc.

Here goes....

I am supplying 125Vac into a R which is a 20kohm resistor where I have a 12V zener in series to GND.

P_loss = (125Vac - 5V)^2 / R

P_loss = 0.72W

So lets say we wait for 1000 secs.

Total Energy (J) = 0.72kJ

Now I am taking into consideration that the SPH of dry air is 0.716 KJ/Kg.K

and Air Density is 1.3 Kg/m3

Therefore Temperate raise should be

Tr = 0.72 / 0.716 / 1.3

= 0.77 K?

Am I missing something here, or is this not he way to calculate heat loss over a resistor?

Someone?

THKS.

Here goes....

I am supplying 125Vac into a R which is a 20kohm resistor where I have a 12V zener in series to GND.

P_loss = (125Vac - 5V)^2 / R

P_loss = 0.72W

So lets say we wait for 1000 secs.

Total Energy (J) = 0.72kJ

Now I am taking into consideration that the SPH of dry air is 0.716 KJ/Kg.K

and Air Density is 1.3 Kg/m3

Therefore Temperate raise should be

Tr = 0.72 / 0.716 / 1.3

= 0.77 K?

Am I missing something here, or is this not he way to calculate heat loss over a resistor?

Someone?

THKS.

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