bts tp 75

1) j = (l₁/e₁)(T₁ – T₂)

j = 3,76.10²(20,97 – 15,65)/20.10^-3

j = 10⁵ W.m^-2

2) R = e/l = 20.10^-3/3,76.10²

R = 5,32.10^-5 m².K.W^-1

3) j = (T₃ – T₂)/R

R = (T₃ – T₂)/j = 4/10⁵

R = 4.10^-5 m².K.W^-1

4) R = e₂/l₂

l₂ = e₂/R = 10.10^-3/4.10^-5

l₂ = 2,5.10² W. m^-1.K^-1

5) l₂ = e₂.l₁.(T₁ – T₃)/e₁.(T₃ – T₂)

Dl₂/l₂ = De₂/e₂ + DT₁/(T₁ – T₃) + DT₃/(T₁ – T₃) +DT₃/(T₃ – T₂) +DT₂/(T₃ – T₂) + De₁/e₁

Dl₂/l₂ = 1/200 + 2/50.5,32 + 2/50.4 + 1/100 = 5.10^-3 + 7,52.10^-3 + 10^-2 + 10^-2

Dl₂/l₂ = 3,25.10^-2

Dl₂ = 3,25.10^-2.2,5.10²

Dl₂ = 8,2 W. m^-1.K^-1

Dl₂ = 9 W. m^-1.K^-1

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