An aluminium rod and copper rod of equal length `1 m` and cross-sectional area `1 cm^(2)` are welded as shown. `K_(A1) = 200 W//m^(@)C, K_(Cu) = 400 W//m^(@)C`. Find heat current

Explanation

Resistance , `R_(Al) = l/(K_(al)A)=(1/(200 xx 10^(-4))) = 50^(@)`C/W
`R_(Cu) = (l/(K_(cu)A)= (1/(400 xx 10^(-4))=25^(@)`C/W
(i) Equivalent resistance, `R_(eq) = R_(AI) + R_(Cu) = 50 +25 = 75^(@)`C/W
Heat current i = (100-25)/(R^(eq)) = 75/75 = 1W`
ii) Equivalent resistance,
`R_(eq) = (R_(Ai).R_(Cu))/(R_(Ai) + R_(Cu)) = (50 xx 25)/(50+25) = 50/3 ^(@)C/W`
Heat current `i=(100-25)/(50//3)=4.5W`