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Re: [Phys-l] Insulation R-value



The thermal resistance R is defined by:
R = delta T/(dQ/dt)
R = r(L/A) = 1/K = (L/A)/k
where
r is the thermal resistivity
k is the thermal conductivity
K is the thermal conductance.

Larry Woolf
General Atomics
www.ga.com
www.sci-ed-ga.org

-----Original Message-----

On Feb 17, 2006, at 11:57 AM, ALVIN BACHMAN wrote:
R is related to the reciprocal of k.
dQ/dt= k A (T1-T0) / L = A (T1-T0) / R

Thanks Al, I was not aware that R is defined differently from k.
Perhaps k should be called thermal konductivity and R should be called
thermal Resistivity. We want house walls to be made from materials that
have large R and small k. Right?
Ludwik Kowalski